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ANSI/PHTA/ICC-11 2026

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American National Standard for Water Quality in Public Pools and Hot Tubs/Spas

Approved January 6, 2026 This standard is managed under the ANSI Continuous Maintenance process. Change Requests (CRs) are accepted continuously and should be submitted through the PHTA website at phta.org.

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ANSI/PHTA/ICC-11 2026

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American National Standard for Water Quality in Public Pools and Hot Tubs/Spas

Pool & Hot Tub Alliance

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1650 King St., Ste. 602

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SECRETARIAT:

703 838-0083

Alexandria, VA 22314

phta.org

Approved January 6, 2026 American National Standards Institute

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American National Standard for Water Quality in Public Pools and Hot Tubs/Spas

American National Standard Approval of an American National Standard requires verification by the American National Standards Institute (ANSI) that the requirements for due process, consensus, and other criteria for approval have been met by the standard developer. Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement has been reached by directly and materially affected interests. Substantial agreement means much more than a simple majority, but not necessarily unanimity.

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Consensus requires that all views and objections be considered and that a concerted effort be made toward their resolution. The use of American National Standards is completely voluntary; their existence does not in any respect preclude anyone, whether they have approved this standard or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the standards.

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The American National Standards Institute does not develop standards and will in no circumstances give an interpretation of any American National Standard. Moreover, no person shall have the right or authority to issue an interpretation of an American National Standard in the name of the American National Standards Institute. Requests for interpretations should be addressed to the secretariat or sponsor whose name appears on the title page of this standard.

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NOTICE: This American National Standard may be revised or withdrawn at any time. The procedures of the American National Standards Institute require that action be taken periodically to reaffirm, revise, or withdraw this standard.

Important Notice about this Document

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This voluntary standard has been developed under the published procedures of the American National Standards Institute (ANSI). The ANSI process brings together volunteers representing varied viewpoints and interests to achieve consensus.

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The Pool & Hot Tub Alliance (PHTA) does not write the standards. Rather, PHTA facilitates a forum for its members, and others interested in pool and spa design and safety, to develop standards through the consensus procedures of ANSI. While PHTA administers the process and establishes rules to promote fairness in the development of consensus, it does not independently test, evaluate, or verify the accuracy of any information or the soundness of any judgments contained in its codes and standards.

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In issuing and making this document available, PHTA is not undertaking to render professional or other services for or on behalf of any person or entity. Nor is PHTA undertaking to perform any duty owed by any person or entity to someone else. PHTA disclaims liability for any personal injury, property, or other damages of any nature whatsoever, whether special, indirect, consequential, or compensatory, directly or indirectly resulting from the publication of, use of, or reliance on this document.

PHTA has no power, nor does it undertake, to police or enforce compliance with the contents of this document. PHTA does not list, certify, test, or inspect products, designs, or installations for compliance with this document. Any certification or other statement of compliance with the requirements of this document shall not be attributable to PHTA. Any certification of products stating compliance with requirements of this document is the sole responsibility of the certifier or maker of the statement. PHTA, its members, and those participating in its activities do not accept any liability resulting from compliance or noncompliance with the provisions given herein, for any restrictions imposed on materials, or for the accuracy and completeness of the text.

Anyone using this document should rely on their own independent judgment or, as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstance. It is assumed and intended that pool and spa users will exercise appropriate personal judgment and responsibility and that public pool and spa owners and operators will create and enforce rules of behavior and warnings appropriate for their facility.

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ANSI/PHTA/ICC-11 2026

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PHTA maintains copyright in all its standards. The ANSI/PHTA/ICC-11 2026 American National Standard for Water Quality in Public Pools and Hot Tubs/Spas is available for adoption and use by the authority having jurisdiction. Its use within a governmental jurisdiction is intended to be accomplished through adoption by reference in accordance with proceedings established in the jurisdiction's laws. “Adoption by reference” means that in the adopting ordinance, the governing body cites only the title, edition, relevant sections or subsections (where applicable), and publishing information of the standard, and that the actual text of the standard is not included in the ordinance. The adoption should recognize PHTA’s copyright to the Standard. PHTA does not waive copyright in its standards by making its standards available for adoption by reference.

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Copyright ©2026 by The Pool & Hot Tub Alliance, 1650 King St., Ste. 602, Alexandria, VA 22314. Printed in the United States of America. All rights reserved. No part of this book may be reproduced, stored in a retrieval system, transcribed, or transmitted, in any form or by any means or method, electronic, mechanical, photocopy, recording, or otherwise, without advance written permission from the publisher: The Pool & Hot Tub Alliance, 1650 King St., Ste. 602, Alexandria, VA 22314.

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The APSP, The Association of Pool & Spa Professionals® word mark, and the APSP logo are trademarks of The Association of Pool & Spa Professionals d/b/a Pool & Hot Tub Alliance registered in the U.S.

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The Pool & Hot Tub Alliance® word mark and logo are registered trademarks of The Association of Pool & Spa Professionals d/b/a Pool & Hot Tub Alliance registered in the U.S.

ICC Trademarks: The “International Code Council,” “International Swimming Pool and Spa Code,” the acronyms “ICC” and “ISPSC,” and the ICC logogram are registered trademarks and service marks of ICC. Use of these marks is not authorized without the express permission of ICC.

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www.iccsafe.org

American National Standard for Water Quality in Public Pools and Hot Tubs/Spas

Foreword This Foreword is not part of the American National Standard ANSI/PHTA/ICC-11 2026. It is included for information only.

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This standard ANSI/PHTA/ICC-11 2026 is a revision of ANSI/APSP/ICC-11 2019.

The ANSI/PHTA/ICC-11 2026 American National Standard for Water Quality in Public Pools and Hot Tubs/Spas, was approved by ANSI on January 6, 2026.

Revision History:

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American National Standard for Water Quality in Public Pools and Spas American National Standard for Water Quality in Public Pools and Spas

Revision Original

Approval Date

November 7, 2018 June 15, 2009

ANSI/APSP-11 2009

Activity

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ANSI/APSP/ICC-11 2019

Title

Designation

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The objective of this standard is to provide minimum guidelines for water quality parameters in public pools, hot tubs, and spas.

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In this revision, those parameters that impact disinfection (sanitizer concentration and pH) have been separated from those parameters that impact only water balance (alkalinity and hardness). The updated standard has not changed the values of the parameters from the previous version. This helps both operators and inspectors prioritize which out-of-range parameters must result in immediate closure, and which do not and can be addressed later.

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It is intended to meet the needs for incorporation into national or regional building codes, and also for adoption by state and/or local municipalities as a local code or ordinance. It is understood that for the sake of applicability and enforceability, the style and format of the standard may need adjustment to meet the code or ordinance style of the jurisdiction adopting this document.

The words “safe” and “safety” are not absolutes. While the goal of this standard is to minimize risk while maximizing the useful life of the venue and its equipment, it is recognized that risk factors cannot, as a practical matter, be reduced to zero in any human activity. This standard does not replace the need for good judgment and personal responsibility. In permitting use of the pool, hot tub, spa, swim spa, or portable spa by others, owners and operators must consider the skill, attitude, training, and experience of the expected user. As with any product, the specific recommendations for installation and use provided by the manufacturer should be carefully observed.

This standard was prepared by the PHTA-11 Standard Writing Committee of the Pool & Hot Tub Alliance (PHTA) in accordance with American National Standards Institute (ANSI)’s Essential Requirements: Due process requirements for American National

ANSI/PHTA/ICC-11 2026

Standards.

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This standard is managed under the ANSI Continuous Maintenance process. Change Requests (CRs) are accepted continuously and should be submitted through the PHTA website at www.phta.org. For questions or more information, contact the PHTA Standards and Codes Department at standards@phta.org.

This standard is published in partnership with the International Code Council (ICC), the leading global source of model codes and standards and building safety solutions that include product evaluation, accreditation, technology, codification, training, and certification. ICC develops and publishes the International Codes, which are adopted as the basis for the building codes used in most states and jurisdictions within the United States as well as many countries around the globe. Additionally, PHTA and ICC have collaborated to develop the first comprehensive model swimming pool and spa code, known as the International Swimming Pool and Spa Code (ISPSC). This landmark document incorporates and references material from ANSI/PHTA standards and ICC model codes, to create a stand-alone code that is consistent with codes and standards from both organizations. The ISPSC and this standard are the result of joint efforts between ICC and PHTA as a service to both the swimming pool and spa community and building code professionals. It is the hope of both organizations that they will lead to enhanced safety for pool and spa users around the world.

American National Standard for Water Quality in Public Pools and Hot Tubs/Spas

Organizations Represented

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Consensus approval in accordance with ANSI procedures was achieved by ballot of the following PHTA Standards Consensus Committee (SCC) and through an ANSI Public Review process. The ANSI Public Review provided an opportunity for additional input from industry, academia, regulatory agencies, safety experts, state code and health officials, and the public at large. Inclusion in this list does not necessarily imply that the organization concurred with the submittal of the proposed standard to ANSI. The voting membership of the SCC is comprised of four interest categories: Producer, User-Government, UserConsumer, and General Interest.

PHTA Standards Consensus Committee (SCC)

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Producer

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American Pools & Spas ...................................................................................................................... Bruce Carney (Chair) Fluidra ......................................................................................................................................................... Philip Escobedo Latham Pool Products, Inc. ........................................................................................................................ Michael Tinkler

User-Government

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Johnson County Department of Health and Environment ............................................................................ Kevin Baugh Utah Department of Health and Human Services ..................................................................................... Sarah Cheshire Cecil County Government ............................................................................................................................. William Funk Public Health Seattle & King County ............................................................................................................ Jun Naotsuka CSG Consultants .......................................................................................................................................... Mike Teemant

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User-Consumer

General Interest

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Tropic Falls at OWA .................................................................................................................................. John Broughton The ZAC Foundation ................................................................................................................................... Megan Ferraro Walt Disney World ...................................................................................................................................... Amrit Singh Gill Abbey's Hope Charitable Foundation ............................................................................................................... Alan Korn City of Plano (Texas) ...................................................................................................................................... Ashley McKay American National Red Cross ................................................................................................................. Stephanie Shook NC Pool School .............................................................................................................................................. Terri Stroupe

IAPMO ............................................................................................................................................................... Sung Choe Chesapeake Aquatic Consultants LLC ..................................................................................................... Frank Goldstein Apothaquali Solutions LLC (AQS) .............................................................................................................. Jennifer Huang International Code Council .............................................................................................................................. Lisa Reiheld RJR Engineering Co., Inc. ................................................................................................................................. Jim Rumen

Non-Voting Government Member

U.S. Consumer Product Safety Commission (CPSC) ............................................................................. Rebekah Kempske

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PHTA-11 Standard Writing Committee (SWC) Voting Members

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Vore & Associates ...................................................................................................................................... Roy Vore (Chair) Counsilman-Hunsaker ..................................................................................................................... Kevin Post (Vice Chair) Solenis ........................................................................................................................................................... Karllee Barton Eastern Kentucky University ............................................................................................................................. Gary Brown Utah Department of Health and Human Services ..................................................................................... Sarah Cheshire Independent Subject Matter Expert .................................................................................................................... Jim Egan Fluidra ........................................................................................................................................................ Philip Escobedo Pentair ...................................................................................................................................................... Kenneth Gregory Bill Hamilton and Associates .................................................................................................................. William Hamilton WTI .................................................................................................................................................................... Jennifer Hill Apothaquali Solutions LLC (AQS) .............................................................................................................. Jennifer Huang Westlake Chemical ........................................................................................................................................... Chris Kareis Periodic Products ............................................................................................................................................. Joe Laurino API Water ...................................................................................................................................................... Jody O’Grady NSF ................................................................................................................................................................. Scott Randall International Code Council .............................................................................................................................. Lisa Reiheld Acqua Pura Pool Service ............................................................................................................................ Matthew Ryther Pool Resources LLC ...................................................................................................................................... Allen Schnaak Biolab, A Kik Consumer Products Company .................................................................................................. John Weber Aquatic Commercial Consulting ....................................................................................................................... Rich Young

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PHTA Staff

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PHTA Program Director, Standards and Technical Services .............................. Genevieve Lynn (PHTA-11 SWC Liaison) PHTA Executive Vice President, Advocacy & External Affairs. ......................................................................... Justin Wiley PHTA Senior Director, Standards and Codes ..............................................................................................Gregory Ceton PHTA Director, Standards .................................................................................................................................. Blake Pavlik PHTA Director, Publications and Standards Development............................................................................April Nowicki

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American National Standard for Water Quality in Public Pools and Hot Tubs/Spas

Table of Contents Scope ............................................................................................................................... 1

Normative References .................................................................................................... 2

Definitions ....................................................................................................................... 3

Reasons for Immediate Pool Closure .......................................................................... 18

Code Compliance ......................................................................................................... 20

Parameters Impacting Disinfection and Public Health .............................................. 21

Parameters Impacting Physical Properties of the Venue........................................... 26

Testing Frequency and Record Keeping .................................................................... 28

Oxidation-Reduction Potential (ORP) ......................................................................... 29

10.

Enzymes ......................................................................................................................... 30

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American National Standard for Water Quality in Public Pools and Hot Tubs/Spas

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1. Scope

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1.1. Public swimming pools and hot tubs/spas. This standard covers public swimming pools and hot tubs/spas to be used for bathing and operated by an owner, licensee, or concessionaire, regardless of whether a fee is charged for use. Public swimming pools covered by this standard. Public swimming pools covered by this standard include all the classes in Section 3 below.

1.1.2.

Pools designed for interaction with marine life have special requirements and are not covered by this standard.

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1.1.1.

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1.2. Variation in methods. This standard provides specifications for water quality parameters, but it does not specify the technologies needed to achieve these values.

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2. Normative References The following documents contain provisions that, through reference in this text, constitute provisions of this American National Standard. At the time of publication, the editions indicated were valid.

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All standards are subject to revision, and parties to agreements based on this American National Standard are encouraged to investigate the possibility of applying the most recent editions of the documents indicated below.

ANSI/ASHRAE 62.1-2022 Ventilation and Acceptable Indoor Air Quality, Table 6-

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1, “Minimum Ventilation Rates in Breathing Zone” (Sports and Entertainment section).

ANSI/NEMA Z535.1-2017 Safety Colors

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ANSI Z535 Standards for Safety:

ANSI/NEMA Z535.2-2011 (R2017) Environmental and Facility Safety Signs

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ANSI/NEMA Z535.3-2011 (R2017) Criteria for Safety Symbols ANSI/NEMA Z535.4-2011 (R2017) Product Safety Signs and Labels for

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Metal Halide Lamps

ANSI/NEMA Z535.5-2011 (R2017) Safety Tags and Barricade Tapes (for

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Temporary Hazards)

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ANSI/NEMA Z535.6-2011 (R2017) Product Safety Information in Product Manuals, Instructions and Other Collateral Materials ANSI/NEMA Z535-2011 Safety color chart NSF/ANSI/CAN 50 - 2024 Equipment and Chemicals for Pools, Spas, Hot Tubs

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and Other Recreational Water Facilities

American National Standard for Water Quality in Public Pools and Hot Tubs/Spas

3. Definitions Acid: A liquid or dry chemical used to lower the pH and/or total alkalinity of pool or hot tub/spa water.

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Acid Demand: A measure of the amount of acid required to lower the pH to a desired level.

Acid Demand Test: A process in which acid of known strength is added in increments to a measured water sample to determine the amount of acid necessary to make an adjustment in a pool to achieve the desired pH.

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Acidic: Having a pH below 7.0. Opposite of Basic.

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AF: See Alkalinity Factor.

Aggressive Water: Water that is corrosive because it is low in pH, and/or calcium hardness, and/or alkalinity. See Langelier Saturation Index (LSI).

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Algae: Plant-like microorganisms that contain chlorophyll.

Algicide: Any chemical or material that kills algae. Also referred to as algaecide. Algistat: Any chemical or material that is able to inhibit the growth of algae.

Alkaline: Having a pH above 7.0.

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Alkalinity: See Total Alkalinity (TA).

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Alkali: A term applied to bases, usually carbonates, bicarbonates, and hydroxides, that raise the pH and alkalinity when added to water.

Alkalinity Factor (AF): A number used to calculate the saturation index of water based on carbonate/bicarbonate alkalinity.

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Ammonia (NH3): A chemical compound of hydrogen and nitrogen that combines with free chlorine in pools to form chloramines or combined chlorine. It also combines with free bromine to form bromamines.

Aquatic Venue: A constructed structure or modified natural structure containing water and intended for recreational or therapeutic use. Exposure to water in these structures may occur by contact, ingestion, or aerosolization. Examples include swimming pools, wave pools, lazy rivers, surf pools, spas, hot tubs, therapy pools, spray pads, waterpark pools, and other interactive water venues.

Available Chlorine: A rating of a chemical’s total chlorine content based on a comparison to elemental (gaseous) chlorine having 100% available chlorine. Back Pressure: Resistance to flow, normally expressed in pounds per square inch (or kilograms per square centimeter). Backwash: The process of cleansing the filter medium and/or elements by the reverse flow of water through the filter.

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Backwash Cycle: The time required to backwash the filter medium and/or elements and to remove debris in the filter vessel. Bacteria: Single-celled microorganisms of various forms, some of which cause infections or disease. See Recreational Water Illness (RWI). Bactericide: Any chemical or material that kills bacteria.

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Balance: In pools and hot tubs/spas, a term used to refer to a condition of the water that is neither scaling nor corrosive. See Langelier Saturation Index (LSI).

Base: A chemical used to raise pH and/or total alkalinity of pool or hot tub/spa water.

Basic: Having a pH above 7.0. Opposite of Acidic.

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Base Demand: A measure of the amount of alkaline material required to raise pH to a predetermined level. This can be accomplished by using a base demand test, whereby a standard base is added by drop to the pH test solution until the desired pH is reached.

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Bather: Any person using a pool, hot tub or spa and its adjoining deck area for the purpose of water sports, recreation, therapy, or related activities. Also referred to as User. Bather Load: The number of persons in the pool/hot tub/spa water at any given moment or during any stated period of time. Also referred to as Swimmer Load.

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BCDMH (Bromo-chloro-dimethylhydantoin, C5H6N2O2BrCl) Products: A solid sanitizer product that is used to generate available bromine. Contains available bromine and available chlorine. Also named 1-bromo-3-chloro-5,5-dimethylhydantoin.

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Biguanide (PHMB): See Polyhexamethylene Biguanide (PHMB).

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Biofilm: A community of microorganisms such as bacteria, algae, or fungi that are encased in a gelatinous matrix and usually attached to surfaces. The matrix protects the microorganisms from harsh environmental conditions and confers greater resistance to sanitizers and algicides. Also referred to as slime.

Bleach: A chlorine source that typically has between 5% and 16% available chlorine. Also referred to as Sodium Hypochlorite (NaOCl) or Liquid Chlorine.

Breakpoint Chlorination: The addition of a sufficient amount of chlorine to water to destroy the combined inorganic chlorine present. Normally, the amount added is equal to ten times the combined chlorine concentration.

Bromamines: Bromine-ammonia compounds exhibiting sanitizing properties similar to Hypobromous Acid (HOBr).

Bromide: A salt that contains a bromide (Br¯) ion. Bromide becomes hypobromous acid (HOBr) when it reacts with oxidizers such as chlorine, ozone, or persulfates. Bromine (Br): The element in several pool/hot tub/spa chemicals that yields hypobromous acid (HOBr) when added to water. See BCDMH, Bromide and Electro

Halogen Generators.

Bromine Feeder: A device to add or deliver bromine sanitizer at a controlled rate.

American National Standard for Water Quality in Public Pools and Hot Tubs/Spas

Bromine Generator: See Electrolytic Chlorine/Bromine Generator. Buffer: Chemical that, when dissolved in water, will resist pH change (See Total

Alkalinity). Also, a chemical solution used to calibrate pH instruments.

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Calcium Carbonate (CaCO3): An insoluble calcium compound that is the major component of scale. CaCO3 occurs normally in limestone, marble, various eggshells, seashells, etc.

Calcium Hardness: A measure of the amount of calcium dissolved in water and expressed in parts per million (ppm) or milligrams per liter (mg/L) as calcium carbonate.

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Calcium Hardness Factor (CF): A number used to calculate the saturation index of water. See Langelier Saturation Index (LSI).

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Calcium Hypochlorite (Ca(OCl)2): A solid white form of chlorine found in both granular and tablet forms (typically 45% to 78% available chlorine). Also referred to as CalHypo.

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Carbon Dioxide (CO2): Common gas found in air and water. Can be used to lower pH in a pool. Caution: See Signal Word. CF: See Calcium Hardness Factor (CF).

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CFU (Colony Forming Units): Used to express the concentration of microorganisms per unit of volume, most often as CFU per ml of bacteria in water.

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Chelating Agent: A chemical used to bind (sequester) metals dissolved in water, to prevent them from precipitating and staining pool/hot tub/spa surfaces. May be referred to as a chelant or Sequestering Agent.

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Chemical Feeder: A device (floating or mechanical) for adding a chemical to pool or hot tub/spa water.

Chemical Feeder Output Rate: Amount of chemical or active ingredient delivered by a feeder per unit time (for example, pounds of chlorine per hour). One pound per hour is equivalent to 0.45 kilograms per hour.

Chloramines: Formed when free chlorine combines with nitrogen-containing compounds (for example, perspiration or ammonia). These compounds can cause eye and skin irritation, have strong, objectionable chlorine-type odors, and low sanitizing capability. Also referred to as Combined Chlorine.

Chlorinated Isocyanurates (ISOS): Sanitizer products that are self-stabilizing due to release of free available chlorine and cyanuric acid when they dissolve. See Sodium Dichlor and Trichloroisocyanuric acid. Chlorinator: A device to add or deliver a chlorine sanitizer at a controllable rate. Chlorine (Cl): The element in several pool or hot tub/spa chemicals that yields hypochlorous acid (HOCl) when added to water. See Calcium Hypochlorite, Sodium Dichlor, Chlorinated Isocyanurates, Sodium Hypochlorite, Chlorine Gas, and

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Trichloroisocyanuric Acid. Chlorine Demand: The amount of chlorine that will be consumed by readily oxidizable impurities in pool or hot tub/spa water. Chlorine Gas (Cl2): A gaseous form of chlorine used to sanitize pools and hot tubs/spas; contains 100% available chlorine.

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Chlorine Generator: See Electrolytic Chlorine/Bromine Generator.

Chlorine Neutralizer: A chemical used to reduce chlorine residuals. See Sodium

Thiosulfate.

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Chlorine Residual: See Residual.

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Circulation System: The mechanical components that are a part of a recirculation system on a pool or hot tub/spa. Circulation equipment may be, but is not limited to, categories of pumps, hair and lint strainers, filters, valves, gauges, meters, heaters, surface skimmers, inlet/outlet fittings, and chemical feeding devices. The components have separate functions but, when connected to each other by piping, perform as a coordinated system for purposes of maintaining pool or hot tub/spa water in a clear and sanitary condition.

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Clarifier: A chemical that causes fine suspended solids in water to combine into filterable clusters. See Flocculant.

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Clarity: The degree of transparency of pool water. Characterized by the ease with which an object can be seen through a given depth of water.

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Combined Chlorine: Also referred to as combined available chlorine. See Chloramines.

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Commercial/Public Pool: Any pool, other than a residential pool, that is intended to be used for swimming or bathing and is operated by an owner, lessee, operator, licensee, or concessionaire, regardless of whether a fee is charged for use (refer to the most current published edition of ANSI/APSP/ICC-1 2014 (R2023) American National Standard for Public Swimming Pools).

Commercial/public pools shall be further classified and defined as follows:

Class A, Competition Pool: Any pool intended for use for accredited competitive

aquatic events such as World Aquatics (formerly known as the Federation Internationale De Natation (FINA)), USA Swimming, USA Diving, USA Synchronized Swimming, USA Water Polo, National Collegiate Athletic Association (NCAA), National Federation of State High School Associations (NFHS), etc. The use of the pool is not limited to competitive events.

Class B, Public Pool: Any pool intended for public recreational use not otherwise classified.

Class C, Semi-Public Pool: Any pool operated solely for and in conjunction with lodgings such as hotels, motels, apartments, condominiums, property owners’ associations, multi-family-owned pools, etc. are covered within the scope of this

American National Standard for Water Quality in Public Pools and Hot Tubs/Spas

standard.

Class D, Other Pool: Any pool operated for medical treatment, therapy, exercise, lap swimming, recreational play, and other special purposes, including, but not limited to, wave or surf action pools, activity pools, splasher pools, kiddie pools, and play areas.

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Class D-1, Wave Action Pools: Wave action pools include any pool

designed to simulate breaking or cyclic waves for purposes of general play or surfing.

Class D-2, Activity Pools: Activity pools are those pools designed for casual

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water play ranging from simple splashing activity to the use of attractions placed in the pool for recreation.

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Class D-3, Catch Pools: Catch pools are bodies of water located at the

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termination of a manufactured waterslide attraction provided for the purpose of terminating the slide action and serving as a means for exit to a deck or walkway area.

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Class D-4, Leisure Rivers: Manufactured streams of near-constant depth in which the water is moved by pumps or other means of propulsion to provide a river-like flow that transports bathers over a defined path that may include water features and play devices.

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Class D-5, Vortex Pools: Circular pools equipped with a method of transporting water in the pool for the purpose of propelling riders at speeds dictated by the velocity of the moving stream. Class D-6, Sand-Bottom Pools: Pools that use sand as an interior floor finish

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over an impervious surface and are equipped to treat and filter the water in the sand areas to maintain a healthful sand condition.

Class D-7, Interactive Play Attractions: Manufactured devices that use

sprayed, jetted, or other water sources contacting the bathers and do not incorporate standing or captured water as part of the bather activity area.

Class D-8, Amusement Park Attractions: Manufactured features designed

for bather interaction or incidental contact with static, splashing, or flowing water.

Class D-9, Natural Bodies of Water: Those natural or man-made aquatic play areas normally regarded as oceans, lakes, ponds, streams, quarries, or bodies of water that the local jurisdiction has designated as Natural Bodies of Water. The design or construction of these facilities is not included in the scope of ANSI/APSP or ANSI/PHTA standards.

Class E: Pools used for instruction, play or therapy and with temperatures above 86° F. Public pools may be diving or non-diving. If diving, they shall be further classified into

ANSI/PHTA/ICC-11 2026

types as an indication of the suitability of a pool for use with diving equipment.

Class A, Competition Pools: Pools specifically designed for diving competitions. Type VI-IX: Public pools suitable for the installation of diving equipment by type. Type N: A non-diving public pool. (No diving allowed.)

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Contaminant: Any physical, chemical, or biological substance in the water that may adversely affect the health or safety of the bather or the quality of the water.

Copper Sulfate (CuSO4): A blue inorganic salt, sometimes used as an algicide. Also referred to as bluestone.

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Cyanuric Acid (CYA): A chemical that reduces the loss of chlorine in water due to the ultraviolet rays of the sun. Also referred to as stabilizer, isocyanuric acid, conditioner, and triazinetrione.

Danger: See Signal Word.

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Diatomaceous Earth (DE): A fine siliceous earth used in filtration, composed chiefly from the fossilized remains of tiny, aquatic organisms called diatoms. Dichlor: See Sodium Dichlor.

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Diethylphenylenediamine (DPD): A chemical testing reagent that measures bromine or free and total chlorine; produces a series of colors from pale pink to dark red. Also named N,N-diethyl-p-phenylenediamine. Dry Acid (NaHSO4): See Sodium Bisulfate.

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Effluent: The outflow of water from a filter, pump, or pool. Electrolytic Chlorinator: See Electrolytic Chlorine/Bromine Generator.

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Electrolytic Chlorine/Bromine Generator: An electrolytic device used to generate free available chlorine or total bromine from either chloride or bromide salts.

Enzyme: Special proteins that catalyze (speed up) those chemical reactions that are important for the life and health of the organism producing them. Enzymes are used to digest or eliminate oils, soap scum, and other organic matter from the water.

EPA-Registered Product: A product bearing the U.S. Environmental Protection Agency (EPA) stamp, indicating that it meets EPA standards for efficacy, human health and safety, environmental impact, use instructions, and product labeling. All products that claim to kill or control bacteria, algae, etc. are required to be registered.

Erosion Feeder: A device that dispenses a sanitizer by directing a flow of water past tablets, briquettes, or pellets. Evaporation: Conversion of liquid molecules into vapor. Fecal Accident: The release of fecal matter into recreational water by humans, pets, or other animals.

American National Standard for Water Quality in Public Pools and Hot Tubs/Spas

Fecal Streptococci: The fecal streptococcus group of microorganisms includes, but is not limited to, the organisms S. faecalis and S. faecium, which inhabit the gastrointestinal tract of warm-blooded animals. These organisms are indicators of contamination in water. The ingestion of the fecal streptococci can cause illness.

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Ferric Iron (Fe+3 or Iron III): Generally insoluble in water, commonly precipitating as rust.

Ferrous Iron (Fe+2 or Iron II): Found in groundwater. It is soluble in water and will generally impart a pale green color. In the presence of oxidizers, it will convert to iron III.

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Filter: A vessel that removes undissolved particles from water by flowing the water through a porous substance (a filter medium or elements).

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Cartridge Filter: A filter that utilizes a porous element that acts as a filter medium. Diatomaceous Earth Filter: A filter that utilizes a thin coating of diatomaceous

earth (DE) or other filter aid over a porous fabric as its filter medium.

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Permanent Medium Filter: A filter that utilizes a filter medium such as sand.

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Filter Aid: Usually refers to powder-like substances such as diatomaceous earth or volcanic ash used to coat a septum-type filter. Also used as an aid to sand filters. Finely divided medium (diatomaceous earth, processed perlite, etc.) is used to coat a septum of a diatomite-type filter.

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Filter Cartridge: A filtering element, usually of fibrous material.

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Filter Cycle: A programmed filtration period. The operating time between cleaning or backwash cycles.

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Filter Element: A device within a filter tank designed to entrap solids and conduct water to a manifold, collection header, pipe, or similar conduit and return it to the pool, hot tub or spa. A filter element usually consists of a septum and septum support, or a cartridge.

Filter Medium: A finely graded material (such as sand, diatomaceous earth, polyester fabric, anthracite, etc.) that removes solid particles from the water.

Filter Sand: A hard silica-like material, free of carbonates or other foreign material, used in sand filters as the media.

Filtration: The process of removing undissolved particles from water by recirculating the water through a porous substance (a filter medium or elements).

Flocculant (floc): A chemical that causes fine suspended solids in water to combine into large clusters that settle out. Flow: The rate of the movement of water, typically in gallons per minute. One U.S. gallon per minute is equivalent to 3.79 liters per minute. Free Available Chlorine (FAC): That portion of the total chlorine that is not combined chlorine and is available as a sanitizer. Also known as Free Chlorine (FC).

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Fungi: A diverse group of eukaryotic single-celled or multinucleate organisms that live by decomposing and absorbing the organic material in which they grow, comprising mushrooms, molds, mildews, smuts, rusts, and yeasts. Galvanic Action: The creation of electrical current by the process of electro-chemical action of dissimilar metals in a liquid.

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Galvanic Corrosion: The deterioration of metal produced when two dissimilar metals are exposed to the electrical current produced by electro-chemical action.

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Halogen: Any of the family of chemical elements including fluorine, chlorine, bromine, and iodine. Chlorine and bromine are commonly used as sanitizers or oxidizers in recreational water.

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Hardness: The amount of calcium and magnesium dissolved in water; expressed as parts per million (ppm) of equivalent calcium carbonate.

Hazard: A condition or set of circumstances that has the potential of causing or contributing to property damage, injury, or death.

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Heat Exchanger: A device with coils, tubes, and plates that takes heat from any liquid (or air) and transfers that heat to another fluid without intermixing the fluids.

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Hot Tub/Spa: A warm water reservoir with hydromassage jets. Hot tubs/spas may be “self-contained” or “non-self-contained.”

Self-Contained Hot Tub/Spa: A hot tub/spa that has a cabinet that houses the

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controls, the pump, heater, and filter. Most “portable hot tubs/spas” are made of an acrylic thermoplastic shell and are surrounded by a cabinet made of wood, alternative wood, or thermoplastic. A “self-contained hot tub/spa” can be moved to another location and reinstalled. A “self-contained hot tub/spa” has all control, water heating, and water circulating equipment as an integral part of the product. A “self-contained hot tub/spa” may be permanently wired or cord-connected. Also known as a “portable hot tub/spa” (refer to the NSPI-2 1999 Standard for Public Spas and ANSI/APSP/ICC-6 2013 (R2023) American National Standard for

Residential Portable Spas and Swim Spas).

Non-Self-Contained Hot Tub/Spa: A “non-self-contained hot tub/spa” does not

have water heating and circulating equipment as an integral part of the product. “Non-self-contained hot tubs/spas” may employ separate components such as an individual filter, pump, heater, and controls, or they may employ assembled combinations of various components.

Hydrogen Peroxide (H2O2): Compound consisting of hydrogen and oxygen supplied in an aqueous solution, used as an oxidizer. Will neutralize halogen sanitizer in water.

Hypobromous Acid (HOBr): A chemical compound that acts as a sanitizer and algicide in water. Hypochlorite: A family of chemical compounds including calcium hypochlorite, lithium hypochlorite, sodium hypochlorite, etc., found in various forms for use as a chlorine

American National Standard for Water Quality in Public Pools and Hot Tubs/Spas

carrier in pool or hot tub/spa water. Hypochlorite Ion (OCI¯): The anion from ionization of hypochlorous acid. Hypochlorous Acid (HOCl): Formed when any chlorinating product is dissolved in water. This is the most active sanitizing form of chlorine. Its dissociation in water into H+ and OCl¯ is pH dependent.

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Increased-Risk Aquatic Venue: An aquatic venue which has an increased risk of microbial contamination due to its primary users being children under the age of 5 and/or people more susceptible to infection, such as therapy patients with open wounds. Examples of increased-risk aquatic venues include spray pads, wading pools, therapy pools, and other aquatic venues designed primarily for children under the age of 5.

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Influent: The water entering a filter or other device.

Interactive Water Play Venue: An aquatic venue, either indoor or outdoor, that includes sprayed, jetted, or other water sources contacting bathers and does not have standing or captured water as part of the bather activity area.

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Ion: An atom or group of atoms that has lost or gained one or more electrons and, as such, possesses an electrical charge.

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Ionization: The process whereby a compound in solution separates into positive ions (cations) and negative ions (anions).

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Ionizer: A device that electro-chemically generates metal ions such as silver and/or copper ions from anodes of these metals.

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Iron: See Ferric Iron and Ferrous Iron.

Isocyanurates: See Chlorinated Isocyanurates.

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Langelier Saturation Index (LSI): A number expressing the degree of saturation of water as related to calcium carbonate solubility and used to predict whether or not water has a tendency to precipitate or dissolve calcium carbonate. Balanced water does not tend to either precipitate or dissolve calcium carbonate. Low LSI values may also indicate that the water is corrosive to metals or other components of a pool or hot tub/spa. Five factors are used in the computation: pH, total alkalinity, calcium hardness, temperature, and Total Dissolved Solids (TDS). Also referred to as Saturation Index.

Leaching: The extracting of a soluble substance from some material, commonly tannic acid from redwood or cedar in hot tubs or a mineral extracted from plaster.

Liquid Chlorine: See Sodium Hypochlorite (NaOCl) or Bleach.

Magnesium Hardness: A measure of the amount of magnesium dissolved in water and expressed in parts per million (ppm) or milligrams per liter (mg/L) as calcium carbonate.

Main Drain: A suction outlet located at the bottom of a pool or hot tub/spa to conduct water to the recirculating pump. Make-Up Water: Water used to fill or refill a pool or hot tub/spa. Also referred to as

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source water. Micron: One millionth of a meter. Used to describe the size of particles that filters are capable of trapping. Microorganism: A microscopic form of life usually referring to bacteria, protozoa, viruses, some fungi and algae in the water.

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Nephelometric Turbidity Units (NTU): Nephelometric Turbidity Units are a qualitative, rather than a quantitative, measurement of the turbidity or cloudiness of a solution, and are a measurement of the amount of light scattered at a 90-degree angle to the incident light. NTUs have no inherent value, and there is no standard conversion between various turbidity units (e.g., NTU or FNU) and quantitative mass measurements (mg/L).

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Nitrogen (N): An element present in ammonia, sweat, urine, fertilizers, and a variety of personal care products and environmental sources. When inadvertently introduced into pools or hot tubs/spas, it readily reacts with chlorine to form chloramines.

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NSF/ANSI/CAN 50: American National Standards Institute accredited standard for the evaluation of materials, components, products, equipment, systems, and treatment chemicals for use at recreational water facilities. This standard includes criteria for equipment performance, safety, and health effects. This standard also includes criteria for health and safety of swimming pool treatment chemicals.

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NSF (formerly the National Sanitation Foundation): An independent, nonprofit, nongovernmental organization of scientists, engineers, educators, and others engaged in research and testing and in the development of standards in multiple public health and environmental areas.

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Oocyst: The thick-walled, environmentally resistant structure released in the feces of infected animals that serves to transfer the infectious stages of sporozoan parasites (e.g., Cryptosporidium) to new hosts.

Organic Matter: Carbon-based substances, generally originating from living organisms, often introduced to pools or hot tubs/spas by bathers and the environment. For example, perspiration, urine, saliva, suntan oil, cosmetics, lotions, and dead skin.

Organisms: Plant or animal life.

ORP: See Oxidation-Reduction Potential.

Orthotolidine (OTO): A colorless reagent that reacts with chlorine or bromine to produce yellow-to-orange colors that indicate the amount of total chlorine or bromine in water. OTO measures total chlorine. Because OTO is a suspected carcinogen and very acidic, use caution when handling this chemical. Oxidation-Reduction Potential (ORP): A measure of the oxidation-reduction potential of chemicals in water. It is generally measured in millivolts by means of an electronic meter and depends upon the types and concentrations of oxidizing and reducing chemicals in the water. Oxidizers: Products used to destroy organic and inorganic contaminants in water.

American National Standard for Water Quality in Public Pools and Hot Tubs/Spas

Ozone (O3): A gaseous molecule composed of three atoms of oxygen. Ozone Generator: A device that produces ozone, generally exposing oxygen or air to corona discharge or ultraviolet light.

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Parts Per Million (PPM): The unit of measurement used in chemical testing that indicates the parts by weight in relation to one million parts by weight of water. It is essentially identical to the term milligrams per liter (mg/L) in pool water.

Pathological Agents: Toxins, microbes, etc. capable of causing diseases.

Pathogens: Disease-causing microorganisms.

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pH: A value used to express acidity of a substance. Expressed as a number on a scale of 0 to 14, with 7.0 being neutral; values less than 7.0 are acidic, and values greater than 7.0 are basic.

pH Meter: An electronic device that measures pH by means of a pH electrode immersed in the water to be tested.

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Polyhexamethylene Biguanide (PHMB): A manufactured organic polymer that is EPAregistered for sanitization of bacteria in recreational water. Pool: A body of water contained in a reservoir used for recreational purposes. See

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Commercial/Public Pool.

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Pool User: Any person using a pool and adjoining deck area for the purpose of water activities or other related activities.

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Potassium Monopersulfate (KHSO5): A solid oxidizer used to prevent the build-up of contaminants in pool and hot tub/spa water. Also referred to as potassium peroxymonosulfate.

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Precipitate: A substance separating out in the form of solid particles from a liquid. A result of a chemical or physical change that settles out or remains as a haze in suspension (turbidity).

Protozoa: Single-celled, eukaryote microorganisms which include amoebas, flagellates, ciliates, sporozoans, and many other forms. The most important protozoa for the pool or hot tub/spa industry are Cryptosporidium, Giardia, and amoeba.

Public Pool: See Commercial/Public Pool.

Pump: A mechanical device, usually powered by an electric motor, that causes hydraulic flow and pressure for the purpose of filtration, heating, and circulation of the pool or hot tub/spa water. Typically, a centrifugal pump design is used for pools, hot tubs or spas. Quaternary Ammonium (QUAT): Organic compound of ammonia used as an algistat and an algicide. Reagent: The chemical formulation used to test various aspects of water quality. Recirculation System: See Circulation System.

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Recreational Water Illness (RWI): An infectious disease spread by swallowing, breathing, or having contact with contaminated water from swimming pools, hot tubs, spas, lakes, rivers, or oceans. The most commonly reported RWI is diarrhea caused by pathogens such as Cryptosporidium, Giardia, Shigella, and Escherichia coli O157:H7. Residual: The measurable sanitizer present in water.

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Risk: The possibility of suffering harm or loss.

Sand Filter: A filter using sand or sand and gravel as a filter medium.

Salinity: The salt content of water.

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Saturation Index: See Langelier Saturation Index (LSI).

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Scale: The precipitate that forms on surfaces in contact with water when evaporation occurs or when the calcium hardness, pH, total alkalinity, or LSI levels are too high. See Langelier Saturation Index (LSI).

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Secondary Disinfection System: Disinfection processes or systems installed in addition to the required primary disinfection systems. Secondary disinfection systems are required for increased-risk aquatic venues.

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Septum: The portion of the filter element consisting of a cloth, wire screen, nylon grid, or other porous material on which the filter medium or filter aid is deposited.

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Sequestering Agent: A chemical that combines with metals keeping them in solution and preventing them from depositing on and staining pool surfaces. Some sequestering agents are chelating agents.

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Shock: Product used to treat microbial infestations as well as destroy non-living organic and inorganic contaminants in water. Because shock products are used to kill bacteria and algae, they must be registered by EPA. See EPA-Registered Product.

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Shock-Oxidizer: Product used to destroy non-living organic and inorganic contaminants in water. This product is neither a sanitizer nor algicide. For control of algae or microorganisms in pool, hot tub or spa water, use an EPA-Registered Product.

Shock-Oxidizer Treatment: The practice of adding a shock-oxidizer product to the water.

Shock Treatment: The practice of adding a shock product to the water.

Signal Word: A visual alerting device in the form of a decal, label placard, or other marking such as an embossing, stamping, etching, or other process that advises the observer of the nature and degree of the potential hazard(s) that can cause property damage, injury, or death. It can also provide safety precautions or evasive actions to take or provide other directions to eliminate or reduce the hazard. Aquatic safety signage shall conform to specifications as described in the ANSI Z535 Standards for Safety series on product safety signs and labels.

Signal word: To convey the gravity of the risk.

American National Standard for Water Quality in Public Pools and Hot Tubs/Spas

Consequences: What are likely to happen if the warning is not heeded. Instructions: Appropriate behavior to reduce or eliminate the hazard. CAUTION: Indicates a potentially hazardous situation that, if not avoided, could result in minor or moderate injury. It may also be used to alert against unsafe practices.

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DANGER: Indicates an imminently hazardous situation that, if not avoided, will

result in death or serious injury. This signal word is to be limited to the most extreme situations.

WARNING: Warning indicates a potentially hazardous situation that, if not

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avoided, could result in death or serious injury.

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Skimmer: A device installed in the pool or hot tub/spa that permits the removal of floating debris and surface water to the filter.

Soda Ash: See Sodium Carbonate.

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Sodium Bicarbonate (NaHCO3): Also referred to as baking soda or sodium hydrogen carbonate. A white powder (pH = 8.3) used to raise total alkalinity in water.

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Sodium Bisulfate (NaHSO4): A granule used to lower pH and/or total alkalinity in water. Also known as Dry Acid. Sodium Carbonate (Na2CO3): A white powder used to raise pH of the water.

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Sodium Dichlor (Sodium Dichloroisocyanurate) (C3N3O3Cl 2Na): Sanitizer product that contains between 56% and 64% available chlorine and is self-stabilizing due to release of free available chlorine and cyanuric acid when it dissolves. Also referred to as sodium dichloro-s-triazinetrione.

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Sodium Hypochlorite (NaOCl): A clear liquid form of an inorganic chlorine compound obtainable in concentrations of 5% to 16% available chlorine. Also referred to as Liquid Chlorine or Bleach.

Sodium Thiosulfate (Na2S2O3): A chemical used to neutralize chlorine.

Spa: A product intended for the immersion of persons in heated water circulated in a closed system and not intended to be drained and filled with each use. A spa usually includes a filter, a heater (electric, solar, or gas), a pump or pumps, and a control, and may include other equipment, such as lights, blowers, and water sanitizing equipment.

Public Spa: Any spa other than a permanent residential spa or residential portable

spa which is intended to be used for bathing and is operated by an owner, licensee, or concessionaire, regardless of whether a fee is charged for use (refer to the most current published edition of NSPI-2, Standard for Public Spas).

Spa User: Any person using a spa and adjoining deck area for the purpose of water activity or other related activity. Special Purpose Pool: A pool intended to be used exclusively for a specific activity, such

ANSI/PHTA/ICC-11 2026

as instruction diving, competition, or medical treatment. Splash Pool: A pool having a water depth not exceeding 18 inches (0.46 meters) that has as its intended primary use random play by small children. Splasher (Wader) Pools: A pool having a maximum water depth of 36 inches (0.91 meters) for the purpose of general play.

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Stabilizer: See Cyanuric Acid.

Substantial Alteration: The alteration, modification, or renovation of an indoor or outdoor aquatic venue or facility where the total cost of the work exceeds 50% of the replacement cost of the venue or facility.

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Superchlorination: The practice of adding a sufficient amount of a chlorinating compound to reduce cloudy water, slime (biofilm) formation, musty odors, or algae and bacteria counts, and/or to improve the ability to maintain sanitizer residuals.

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Supplemental Treatment Systems: Systems or processes which are not required on an aquatic venue for health and safety reasons but may be used to improve water quality and/or enhance overall system performance. Swimmer Load: See Bather Load.

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Swimming Area: Area of pool in excess of 3 feet (0.91 meters) in depth that is devoted to swimming.

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TDS Factor: A number used when determining the saturation index of water. See Langelier Saturation Index (LSI).

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Temperature Factor (TF): A number used when determining the saturation index of water. See Langelier Saturation Index (LSI).

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Test Kit: Equipment used to determine specific chemical residual and physical properties of water.

Therapy Pool: A pool used exclusively for aquatic therapy, physical therapy, and/or rehabilitation to treat an injury, illness, or other medical condition.

Titration: A method for measuring alkalinity, hardness, available chlorine, or other such chemical parameters by measured addition of reagents that yield a foreseeable end point as indicated by a change in color.

Total Alkalinity (TA): A measure of the pH buffering capacity of water. Alkalinity is generally expressed in terms of the equivalent concentration of calcium carbonate in ppm (or mg/L). Total Alkalinity (TA) Factor: A number used when determining the saturation index of water. See Langelier Saturation Index (LSI). Total Chlorine (TC): The sum of both the free available and combined chlorines.

Total Dissolved Solids (TDS): The measure of the total amount of dissolved matter in water.

American National Standard for Water Quality in Public Pools and Hot Tubs/Spas

Toxic: A substance having an adverse physiological effect on human beings or other living organisms. Trichlor: A form of organic chlorine, most commonly found in compressed form (tablets or sticks). See Trichloroisocyanuric Acid.

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Trichloroisocyanuric Acid (C3N3O3Cl3): Sanitizer product that is self-stabilizing due to release of free available chlorine and cyanuric acid when it dissolves. A form of organic chlorine that reacts with water to form 90% available chlorine and cyanuric acid. Also referred to as trichloro-s-triazinetrione.

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Turbidity: Cloudy condition of water due to the presence of extremely fine particulate materials in suspension that interfere with the passage of light.

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Ultraviolet (UV) Light: UV light is often characterized as UV-A, UV-B, or UV-C, indicating wave lengths of 315 to 400 nanometers (nm), 290 to 315 nm, and 220 to 290 nm, respectively. UV-C is the germicidal region of the light spectrum that is used to deactivate microorganisms and can be generated artificially with gaseous lamps.

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User: Any person engaging in water activities or related activities at a pool, hot tub or spa, including the adjoining deck. See Bather.

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User Load: The total number of persons permitted in the pool or hot tub/spa complex at any given time. See Bather Load.

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Volume: The capacity of a specified container (e.g., a pool or hot tub/spa) expressed in gallons or liters. One U.S. gallon is equivalent to 3.79 liters.

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Vomit Accident: An act or instance of disgorging the contents of the stomach through the mouth into recreational water by humans, pets, or other animals.

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Wading Pool: A pool with a depth not exceeding 2 feet (0.61 meters) used exclusively for wading and intended for use by young children.

Warning: See Signal Word.

ANSI/PHTA/ICC-11 2026

4. Reasons for Immediate Pool Closure 4.1. The pool or hot tub/spa shall be closed immediately if any of the following water quality conditions occur: 4.1.1.

The water is not clear enough in …

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4.1.1.1. Pools: … to clearly see the main suction outlet (main drain cover) from any point on the deck up to 30 ft. (9.1 m) away in a direct line of sight, or

4.1.2.

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4.1.1.2. Hot tubs/spas: … to see the deepest point of the bottom when the water is not turbulent. The sanitizer concentration is below a minimum standard.

4.1.2.1. Pools:

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4.1.2.1.1. Chlorine with 50 ppm or less of cyanuric acid: free chlorine less than 1.0 ppm (1.0 mg/L)

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4.1.2.1.2. Chlorine with 51 ppm or more of cyanuric acid: free chlorine less than 2.0 ppm (2.0 mg/L) 4.1.2.1.3. Bromine: total bromine less than 2.0 ppm (2.0 mg/L)

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4.1.2.1.4. PHMB: less than 30 ppm as product (less than 10 ppm as active)

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4.1.2.1.5. Other systems: If it is below the product manufacturer’s EPAregistered label for use and/or operation 4.1.2.2. Hot tubs/spas:

4.1.2.2.1. Chlorine with 50 ppm or less of cyanuric acid: free chlorine less than 2.0 ppm (2.0 mg/L) 4.1.2.2.2. Chlorine with 51 ppm or more of cyanuric acid: free chlorine less than 3.0 ppm (3.0 mg/L) 4.1.2.2.3. Bromine: total bromine less than 4.0 ppm (4.0 mg/L) 4.1.2.2.4. PHMB: less than 30 ppm as product (less than 10 ppm as active) 4.1.2.2.5. Other systems: If it is below the product manufacturer’s EPAregistered label for use and/or operation

4.1.3.

The pH is below 7.2 or above 7.8.

American National Standard for Water Quality in Public Pools and Hot Tubs/Spas

The water temperature exceeds 104°F (40°C).

4.1.5.

There are feces or vomit in the water.

4.1.6.

There is an incident or condition that presents an immediate and obvious risk to bather health and safety, or if local codes require the closure of the facility.

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4.1.4.

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4.2. The pool or hot tub/spa shall remain closed until the problem is corrected.

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5. Code Compliance

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Pools and hot tubs/spas covered by this standard shall be operated to comply with all local, state, and federal codes governing safety and environmental regulations.

American National Standard for Water Quality in Public Pools and Hot Tubs/Spas

6. Parameters Impacting Disinfection and Public Health

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Parameters in this section shall be followed to minimize health and safety hazards for bathers.

6.1. A residual of an EPA-registered sanitizer shall be present at all times and in all areas of the pool or hot tub/spa. One of the following EPA-registered sanitizer systems shall be used: Chlorine

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Bromine

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PHMB

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Metal-based systems

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•

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Not all of these sanitizer systems are approved for all pool and hot tub/spa uses. The use of the product shall comply with the EPA label as well as applicable codes and regulations.

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The one exception to having an EPA-registered sanitizer is on-site electrolytic halogen generation. The use of electrolytic halogen generators (i.e., chlorine and bromine generators) shall comply with Section 6.2 or 6.3. Electrolytic halogen generators shall be certified to NSF/ANSI/CAN 50 - 2024. Free available chlorine (FAC)

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6.1.1.

6.1.1.1. Free available chlorine – pools:

6.1.1.1.1. A minimum free available chlorine residual of 1.0 ppm (1.0 mg/L) shall be maintained at all times and in all areas of a pool. 6.1.1.1.2. A minimum free available chlorine residual of 2.0 ppm (2.0 mg/L) shall be maintained at all times and in all areas of a pool with a cyanuric acid concentration in excess of 50 ppm. 6.1.1.1.3. A maximum of 4.0 ppm (4.0 mg/L) shall not be exceeded when the pool is open to the public.

6.1.1.2. Free available chlorine – hot tubs/spas: 6.1.1.2.1. A minimum free available chlorine residual of 2.0 ppm (2.0 mg/L) shall be maintained at all times and in all areas of a hot

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tub/spa. 6.1.1.2.2. A minimum free available chlorine residual of 3.0 ppm (3.0 mg/L) shall be maintained at all times and in all areas of a hot tub/spa with a cyanuric acid concentration in excess of 50 ppm.

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6.1.1.2.3. A maximum of 5.0 ppm (5.0 mg/L) shall not be exceeded when the hot tub/spa is open to the public.

6.1.2.

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Note: The U.S. Environmental Protection Agency (EPA) has established a maximum chlorine concentration of 4.0 ppm (4.0 mg/L) for re-entry of swimmers or bathers into pool water based on drinking water limits. 1 The maximum they have set for hot tubs/spas is 5.0 ppm (5.0 mg/L). However, state or local health codes may allow or require the use of chlorine concentrations above 4.0 ppm (4.0 mg/L) for pools and 5.0 ppm for hot tubs/spas. Bromine

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6.1.2.1. Pools: A minimum bromine residual of 2.0 ppm (2.0 mg/L) (expressed as Br2) shall be maintained at all times and in all areas of the pool. The bromine concentration shall not exceed the maximum indicated on the label of the EPA-registered product when the pool is open to the public.

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6.1.2.2. Hot tubs/spas: A minimum bromine residual of 4.0 ppm (4.0 mg/L) (expressed as Br2) shall be maintained at all times and in all areas of the hot tub/spa. The bromine concentration shall not exceed the maximum indicated on the label of the EPA-registered product when the hot tub/spa is open to the public.

6.1.2.3. Operators shall refer to the manufacturer’s product label for specific use concentrations since allowable concentrations can vary depending upon which brominating compound is used. PHMB (Polyhexamethylene biguanide). The concentration of PHMB shall be maintained between a minimum of 30 ppm and a maximum of 50 ppm (as product) for pools and hot tubs/spas.

6.1.3.

U. S. Environmental Protection Agency (EPA), Reregistration Eligibility Decision (RED): Chlorine Gas (1999). Office of Pesticide Programs (OPPT), EPA 738-R-99- 001.

American National Standard for Water Quality in Public Pools and Hot Tubs/Spas

6.2. Secondary Disinfection Systems 6.2.1.

All new construction or substantial alteration of the following increasedrisk aquatic venues shall be required to use a secondary disinfection system. 1. Wading pools

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2. Interactive water play venues

3. Other aquatic venues designed primarily for children under the age of 5

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4. Therapy pools

Secondary disinfection systems may be installed on other aquatic venues.

6.2.3.

Secondary disinfection systems shall be listed and labeled to NSF/ANSI/CAN 50 - 2024, by an ANSI-accredited certification organization and shall be installed according to the manufacturer’s directions.

6.2.4.

Secondary disinfection systems shall be designed to achieve a minimum 3-log (99.9%) reduction in the number of infective Cryptosporidium parvum oocysts per pass through the secondary disinfection system at the maximum flow rate.

6.2.5.

Ozone

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6.2.2.

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6.2.5.1. Ozone shall be used only in conjunction with an EPA-registered sanitizer or electrolytic halogen generator.

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6.2.5.2. Ozone concentrations in the air above the pool or hot tub/spa water shall not exceed Occupational Safety and Health Administration (OSHA) permissible exposure limits, currently 0.1 ppm over an 8hour Time Weighted Average. 2

6.2.5.4. When ozone is used for indoor installations, air monitoring is required in the equipment room.

6.2.5.3. The ozone concentration in the air above the pool or hot tub/spa water may also not exceed the Short-Term Exposure Limit (STEL) of 0.3 ppm for any 15-minute period.

29 CFR 1910.1000 Table Z-1, Feb. 28, 2006. www.osha.gov or www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9992

ANSI/PHTA/ICC-11 2026

6.2.6.

Ultraviolet light (UV)

6.2.6.1. Germicidal UV systems shall be used only in conjunction with an EPAregistered sanitizer or electrolytic halogen generator.

6.3. Supplemental Treatment Systems Secondary disinfection systems. Secondary disinfection systems (such as ozone or UV) can also be considered supplemental systems if they are not required at the venue (as defined in Section 6.2.1) and their intent is to be used to enhance the primary sanitizer and improve water quality.

6.3.2.

Metal-based systems

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6.3.2.1. Any metal-based systems used shall be used in conjunction with an EPA-registered sanitizer. Follow the product manufacturer’s EPAaccepted label for use and/or operation requirements.

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6.3.2.2. Electrolytic copper/silver and copper ion generation systems shall be certified to NSF/ANSI/CAN 50 - 2024.

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6.4. Cyanuric Acid. When used, cyanuric acid concentrations shall not exceed 100 ppm.

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6.5. pH. The pH shall be maintained between 7.2 and 7.8. 6.6. Water Clarity

Pools. The bottom of the pool at its deepest point shall be clearly visible and sharply defined from any point on the deck up to 30 ft. (9.1 m) away in a direct line of sight from the main drain.

6.6.2.

Hot Tubs/Spas. The bottom of the hot tub/spa at its deepest point shall be clearly visible. (This test shall be performed when the water is in a nonturbulent state and bubbles have been allowed to dissipate.)

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6.6.1.

6.7. Temperature. Water in contact with bathers shall never exceed a temperature of 104°F (40°C). 6.8. Contaminants 6.8.1.

Algae. Remedial action shall be taken when algae is visible.

6.8.2.

Combined Chlorine

6.8.2.1. The concentration of combined chlorine in pools shall not exceed 0.4 ppm.

American National Standard for Water Quality in Public Pools and Hot Tubs/Spas

6.8.2.2. The concentration of combined chlorine in hot tubs/spas shall not exceed 0.4 ppm. Foam. There shall be no persistent foam (foam remaining in a hot tub/spa after the jets are turned off).

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6.8.3.

ANSI/PHTA/ICC-11 2026

7. Parameters Impacting Physical Properties of the Venue

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Parameters in this section have long-term impact on the physical integrity of the venue but have limited to no impact on the health and safety of swimmers. Operating outside of the limits established in this section may shorten the venue’s useable life but are not issues that immediately impact user health. Operators, however, are expected to begin remediation efforts promptly, although they are not obligated to close the venue immediately for these adjustments.

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7.1. Water Balance Parameters Other than pH

Total Alkalinity. Total alkalinity shall be maintained between a minimum of 60 and a maximum of 180 ppm as CaCO3.

7.1.2.

Calcium Hardness. Pool water calcium hardness shall be maintained between a minimum of 150 and a maximum of 1,000 ppm as CaCO3. In hot tubs/spas, calcium hardness shall be maintained between a minimum of 100 and a maximum of 800 ppm as CaCO3.

7.1.3.

Total Dissolved Solids (TDS). Total Dissolved Solids shall not exceed 1,500 ppm above the concentration at start-up. Start-up TDS includes source water TDS and any sodium chloride added.

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7.1.1.

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7.2. Air quality

The indoor pool and hot tub/spa area shall have its own dedicated ventilation equipment.

7.2.2.

All pools and their related components that are installed in an indoor environment shall comply with the ventilation requirements of ANSI/ASHRAE 62.1-2022, Table 6-1.

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7.2.1.

7.3. Water replacement

7.3.1.

Hot Tubs/Spas. The Water Replacement Interval (WRI) and Total Dissolved Solids (TDS) shall both be monitored. The water shall be replaced when either of the following conditions is met: 1. TDS has increased to 1,500 ppm greater than TDS at hot tub/spa start-up; or 2. The WRI is less than or equal to the number of days since the last time the water was replaced. The WRI is calculated as follows: WRI (Days) = (1/3) x (Hot Tub Volume in U.S. Gallons) / (Number of Bathers per Day)

American National Standard for Water Quality in Public Pools and Hot Tubs/Spas

Note: Start-up TDS includes source water TDS and any sodium chloride or sodium bromide added. Swimming Pools. It is recommended that regular water replacement be applied to pools, although certain circumstances may prohibit this practice (e.g., drought conditions) or make it unnecessary (e.g., supplementary water treatments such as reverse osmosis to extract contaminants from the water).

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7.3.2.

ANSI/PHTA/ICC-11 2026

8. Testing Frequency and Record Keeping 8.1. The parameters for sanitizer, pH, clarity, and water temperature shall be met at all times. Exception: when shocking the pool, when closed for the season, or similar activities.

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8.2. Testing frequency shall be sufficient to ensure that the standards set forth in this document for sanitizer, pH, clarity, and water temperature (in a hot tub/spa) are met at all times. Permanent records of testing results shall be maintained for a minimum of one year.

American National Standard for Water Quality in Public Pools and Hot Tubs/Spas

9. Oxidation-Reduction Potential (ORP) 9.1. When an ORP controller is used, it shall not be relied upon as a method for measuring the concentration of sanitizer in the water.

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9.2. The sanitizer residual shall be measured with chemical methods capable of detecting the specific sanitizer (e.g., DPD for free available chlorine) to ensure that the minimum concentration is maintained.

ANSI/PHTA/ICC-11 2026

10. Enzymes When used, enzymes shall be certified to NSF/ANSI/CAN 50 - 2024.

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American National Standard for Water Quality in Public Pools and Hot Tubs/Spas

ANSI/PHTA/ICC-11 2026

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This standard provides recommended minimum updated guidelines for the specifications for water quality parameters in public pools, hot tubs, and spas. It covers a range of values that are acceptable for pool, hot tub, and spa operation relating to various chemicals.

Approved January 6, 2026

5272ND

1650 King St., Ste. 602 Alexandria VA 22314 (703) 838-0083 standards@PHTA.org | phta.org