Assessment of Water Loss and Non-Revenue Water in Urban Distribution Networks: A Chemical Engineering Perspective from Katsina State

Non-revenue water constitutes a major financial and operational challenge for state water boards in North West Nigeria, including the Katsina State Water Board, where physical losses from aging pipe networks and commercial losses from metering inaccuracies undermine water supply sustainability. This study assesses the magnitude and causes of non-revenue water in the Katsina Municipal water distribution network, focusing on water quality changes associated with losses, pipe material deterioration, and residual chlorine decay. Water balance analysis was performed for three distribution zones using the International Water Association standard water audit methodology, incorporating production meter data, sample meter readings, and field leak surveys. Disinfection residual decay profiling was conducted along main distribution arteries, with sampling at 6-hour intervals for chlorine, turbidity, pH, and bacterial growth indicators. Non-revenue water was estimated at 48.3% of system input volume, of which real losses comprised 71% and apparent losses 29%. Residual chlorine fell below the 0.2 mg/L WHO minimum at distances greater than 8 km from the treatment plant due to high pipe surface area-to-volume ratios in undersized mains and organic matter accumulation in corroded iron pipes. The study recommends pressure management zones, targeted pipe rehabilitation, and chloramine secondary disinfection to reduce both physical losses and disinfection decay in the Katsina distribution network. Keywords: non-revenue water, distribution network, chlorine decay, Katsina State, water loss