Evaluation of Drinking Water Treatment Plant Performance in Gusau, Zamfara State

This study evaluates the performance of the Gusau Water Treatment Plant in Zamfara State, North West Nigeria, examining its capacity to consistently deliver water of acceptable quality under prevailing raw water conditions and operational practices. Access to reliably treated piped water in Gusau is limited by both treatment plant performance deficiencies and distribution system losses, and an engineering evaluation of the treatment plant's performance provides the basis for targeted improvement interventions. Process performance was assessed by sampling raw water, settled water, filtered water, and final treated water at each major treatment stage on a weekly basis over three months, covering both dry season and early rainy season conditions. Parameters measured include turbidity, pH, free chlorine residual, total coliform, E. coli, aluminium residual, and colour. Hydraulic loading rates were compared against design criteria. Results show that turbidity removal through coagulation, sedimentation, and filtration meets the WHO guideline of one nephelometric turbidity unit at the plant outlet during dry season low-turbidity conditions but fails during the peak rainy season when raw water turbidity spikes above 800 NTU overwhelm the coagulant dosing system. Free chlorine residual at the distribution entry point is inadequate at less than 0.5 milligrams per litre on several sampling dates, raising microbiological risk in the distribution system. Aluminium residual in treated water occasionally exceeds the WHO guideline. The study recommends an automated coagulant dosing upgrade and distribution system residual chlorine monitoring. Keywords: water treatment, drinking water quality, turbidity, chlorination, Zamfara State.