Assessing the spatial distributions and relationship of pH and chlorine for treated water in Jinja NWSC service Area.

Abstract

NWSC is responsible for the treatment and distribution of piped water in Jinja district. The raw water from Lake Victoria is treated at Masese water treatment plant and pumped to a high level reservoir at Rubaga hill that distributes it by gravity to other low level reservoirs and distribution pipes where the final consumers are served. The bacteriological quality of water can deteriorate during distribution, as well as due to contamination from exposure to external pollutants due to pipe leaks, burst and repairs (World Health Organization, 1996). As such, periodic checks on the quality of drinking water are of paramount importance to NWSC to ensure that the water supplied to its customers is within the stipulated national standards. Treated water quality describes the quality parameters set for drinking water in the distribution network. The drinking water quality parameters checked in Jinja are: pH, Turbidity, Chlorine, Electrical conductivity, Color and Total Suspended Solids. These are checked in a laboratory for specific sample points selected throughout the distribution network to ensure the quality of treated water is within minimum UNBS national standards. The acceptable range for pH is 6.5- 8.5, while that for chlorine is 0.2-0.5 mg/l. The sample points are selected based on distance from reservoirs, settlement patterns, population and sanitary conditions. At the NWSC water quality laboratory in Jinja, the analysis of parameter concentrations is based on statistical methods using MS Excel. There is no spatial investigation carried out to determine the locations of areas within the network that are prone to undesirable concentrations of pH and chlorine. Neither is analysis undertaken to determine spatial outliers and clusters that could be the result of potential contamination points in the distribution network. This study utilizes geospatial techniques to assess the spatial distributions and relationship of pH and chlorine concentrations of treated water for selected sample points in the Jinja water supply network. Historical parameter data over a period of five months will be analyzed in the study. The main benefit from the investigation will be monthly thematic maps showing hotspots of high concentrations for pH and chlorine, as well as the locations within the network whose concentrations are considered to be outliers and clusters.