THE IMPACT OF WATER DISTRIBUTION SYSTEM ON EVENTUAL QUALITY: A CASE STUDY OF THE UNIVERSITY OF ILORIN WATER SYSTEM

Abstract

The impact of distribution network on eventual quality of water delivered was studied using the quality of water from the Unilorin drinking water distribution system as a case study. A total of 45 samples were collected from 15 locations and water quality parameter monitored monthly between February and April 2010. The quality parameter measured were temperature, pH, conductivity, total alkalinity, total dissolved solid, total hardness, calcium, magnesium, sulphate, phosphate, nitrate, chloride and residual chlorine using standard methods. Mn, Fe, Zn, Pb, Cd, and Cr contents of the water samples were determined by Atomic Absorption Spectrophotometer after digestion using aqua-regia. The data showed the variation of the investigated parameters as follows: temperature 30-33°C, pH 6.98-7.85, conductivity (EC) 94-187µScm-1, total dissolved solid 630-980mg/L, total hardness 40-80mg/L calcium 25-53mg/L, magnesium 14-32mg/L, chloride 10.6-16.0mg/L, phosphate 0.4-1.8mg/L, sulphate 11.5-16.3mg/L, nitrate 2.0-5.8mg/L, residual chlorine 0.1-1.2mg/L, Mn <0.01-0.87mg/L, Fe 0.11-14.6mg/L, Zn 0.08-11.1mg/L, Pb <0.01-1.17mg/L, Cu <0.01-3.62mg/L. Chromium and cadmium concentrations in all the water samples were below detection limit (0.01mg/L). In general, parameters such as conductivity, hardness, calcium and magnesium content, Total dissolved solid exhibited higher concentrations in the raw dam water compared to the drinking water collected along the distribution lines. The concentrations of investigated parameters were all within the permissible limits of the World Health Organization water quality guidelines except Mn, Fe, Zn and Pb which were occasionally above the regulatory limits. This has been attributed to their possible release into the distribution system from the pre-deposited iron and manganese oxides on the interior surface of iron and PVC pipes used for water distribution, as well as products of corrosion of the metallic pipes.

Author

Adekola, F. A, *Abdus-Salam, N., Adegoke, H. and *Majasan J. O. Department of Chemistry, University of Ilorin, Ilorin, Nigeria