International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 12 Issue: 09 | Sep 2025
p-ISSN: 2395-0072
www.irjet.net
Water Age Analysis of a Distribution Network using EPANET 2.2 Soumitra Ganguly1 1Consulting Environmental Engineer, Retired Superintending Engineer, PHED, Govt. of West Bengal
---------------------------------------------------------------------***--------------------------------------------------------------------residence times. While decay models predict concentration over time and distance, they cannot fully explain persistent systems governs disinfectant persistence, microbial risk, and under-chlorination in some areas. A key overlooked factor is user acceptability. This study applies EPANET 2.2 to a rural Water AGE—the residence time of water in the system— multi-village Water Distribution Network (WDN) in West which directly influences disinfectant persistence, microbial Bengal having low demand and minimum permissible regrowth, and overall acceptability. Water age analysis diameter (≈90 mm OD; ≈80.4 mm ID) under extended period addresses this by showing how hydraulic residence times simulation (EPS) to quantify systemwide water age and govern chlorine behavior throughout the network. identify vulnerability zones. Using assumed diurnal peaking factors (PF) over 96 hours (Case-1) and two simplified 1.1 Why Age Matters constant-demand scenarios (Case-2; PF=1 and PF=3). It is shown that in Case-1 (i) average network age during 73–96 h ranges ~9.9–16.3 h (mean ≈12.4 h) while maximum node age Rural water supply systems in India typically have low ranges ~30.1–39.7 h (mean ≈35.2 h); whereas in Case-2 (ii) demand and long, scattered pipelines. Minimum diameters of terminal segments exhibit very long travel times (≈17.7 h for a 75–90 mm (OD) are generally used due to regulatory norms. length of 785 m at PF=1, improving to ≈5.9 h at PF=3). The Chlorine is usually dosed only once at the headworks, after results indicate persistent risk of low chlorine residuals at the which it decays progressively as water travels downstream periphery under single-point chlorination. (B. Kowalska et al., 2006). Extended residence times accelerate decay (Hossein Shamsaei et al., 2013), creating zones vulnerable to loss of residuals. The findings highlight that water age analysis provides an essential diagnostic tool for rural WDNs, revealing hidden 1.1.1 Chlorine Residuals and Regulatory vulnerabilities not captured by conventional chlorine decay modeling alone. Incorporating water age into routine water Significance quality assessments can guide the placement of chlorine booster stations, inform dosing strategies, and support more International guidelines, including those of the WHO, resilient distribution system design and operation. The study stipulate that free residual chlorine concentrations below demonstrates that water age analysis offers a more 0.2–0.3 mg/L are undesirable for safe supply (Julius Ceaser, comprehensive understanding of the fate of residual chlorine 2024). Adequate residuals at all network nodes serve as a in a rural WDN. safeguard against microbial contamination, ensuring bacteriological safety of the distributed water. However, excessive dosing to compensate for decay is not a Key Words: Rural Water Supply, Water Distribution sustainable strategy, as it can lead to the formation of Network, Water Quality Analysis, Hydraulic Analysis, disinfection by-products (DBPs) and generate consumer Water AGE Analysis, Residual Chlorine, EPANET, Extended acceptability issues (Ababu T. Tiruneh et al., 2019; Denis Period Simulation. Nono et al., 2019; Hossein Shamsaei et al., 2013). Residual chlorine is not constant across a distribution system; rather, 1. INTRODUCTION it fluctuates spatially and temporally depending on flow dynamics and local residence time. In water supply systems, safety depends not only on treatment at the source but also on conditions during 1.1.2 Chlorine Decay Processes distribution. Water that is safe at the treatment plant/ source may become contaminated due to leakages, microbial growth on pipe walls, and other factors. Chlorination is the Chlorine decay during transport through a WDN occurs most widely used disinfection method, valued for both its predominantly via two pathways: bulk decay (kb) and wall effectiveness against bacteria and its residual protection (B. decay (kw). Kowalska et al., 2006; Denis Nono et al., 2019; J. J. Vasconcelos et al., 1997). The magnitude of bulk decay is influenced by water quality parameters such as natural organic matter, inorganic However, chlorine effectiveness declines with time as it constituents, and temperature. Conversely, wall decay is decays during transport, with higher decay linked to longer largely determined by the material, condition, and age of the
Abstract - Age (residence time) of water in distribution
© 2025, IRJET
|
Impact Factor value: 8.315
|
ISO 9001:2008 Certified Journal
|
Page 397