Simulation of Chlorine Decay in Water Distribution Networks Using EPANET – Case Study

Abstract

Deterioration of water quality in distribution networks has a great impact on human health and public acceptance of tap water reaching them. Residual chlorine should be maintained through network pipes to prevent contamination and microbial regrowth. This paper investigates the ability of EPANET 2.0, a free software developed by United States Environment Protection Agency (USEPA), to simulate residual chlorine decay through water networks, taking water-age analyses into consideration, and assesses the feasibility of using it as a measuring and controlling tool to estimate and predict chlorine concentration at different water network points. A study was performed on drinking water network of 6^th of October city, where field measurements were done, while data required as program inputs were taken from the daily records of the 6^th of October and El-Shaikh Zayed WTPs. The network model was calibrated to minimize error in program results. Errors were evaluated using statistical analyses. The calculated concentrations by the calibrated model were very close to the actual concentrations measured in field at different sampling points for different sampling days. Moreover, EPANET showed that for the water network concerned in this study, chlorine concentrations at network extremities did not recede 0.5 mg/l, the minimum allowable limit established in the Egyptian Code of Practice (ECP), even for those points having water age greater than 24 hours.

Keywords: chlorine decay, water quality, water distribution networks, EPANET, water-age