Assessment Of Residual Chlorine And Its Decay In Stored Water From Communities In Cape Coast Metropolis, Ghana

Abstract

Residual chlorine in tap water has been of great concern worldwide especially in developed countries, as disinfected water at the water treatment plant may be polluted again when the water is being transported. The residual chlorine content in tap water samples distributed through pipeline by the Ghana water company limited Brimsu Headworks, to the populace of Cape Coast Metropolis was assessed for residual chlorine in eight weeks. This study ascertained the residual chlorine content of the tap water and its safety level for human use; the similarity in the residual chlorine contents. Samples were collected weekly from eleven suburbs and the residual chlorine analysed by spectrophotometric method using diethyl-p-phenylenediamine (DPD) regent. Two sets of distinct residual chlorine concentrations were observed; with means (mean ± CV) 0.199±1.833 ppm for samples from Abura, Pedu, Brafoyaw, Duakor, University of Cape Coast Lec Village; and 0.317±1.208 ppm for samples from Elmina, UCC Campus, Kotokoraba, Kwaprow, Amamoma and Akotokyir. The highest residual chlorine content was found at Amamoma, and the lowest at Pedu. Even though the tap water was from the same source, it had varying levels of residual chlorine. One-way ANOVA revealed that there was statistically significant difference in residual chlorine levels in tap water at each community (p = 0.00 < α = 0.05) and (Fcrit = 1.876 < Fstatistic = 1946.976). The pH ranged from 6.50-7.20, and showed no significant difference. The was no significant correlation between the pH and the residual chlorine content. A hierarchical cluster analysis showed 50 % similarity for Akotokyir and Kotokoraba, Abura and Elmina, 58%; Brafoyaw and UCC had similar levels of 65%. No sample had similarity level above 70 %. The residual chlorine decay in stored tap water kept in different storage conditions over the 8 days revealed that, for water stored in a room, the level of residual chlorine reduced by 65.38% for tap water stored in covered container and 64.23% for tap water kept in uncovered container. For tap water kept outdoor, residual chlorine reduced by 65.02% for tap water kept in uncovered container and 63.6% for tap water in a covered container. All the tap water sampled had residual chlorine within the 0.2- 0.5 ppm guideline set by World Health Organization (WHO). The free chlorine and bacterial should be assessed concurrently.