Assessment of physico-chemical and bacteriological quality of drinking water at sources and household in Adama Town, Oromia Regional State, Ethiopia

Abstract

Water quality is a critical factor affecting human health and welfare. This study aimed at examining the physico-chemical and bacteriological quality of drinking water in Adama town. A total of 107 triplicate water samples were examined; 1 from inlet point (raw water), 1 from outlet (the water after treatment, 1 from reservoir (treated water stored), 52 from pipe water and 52 from systematically selected household’s containers. Six physico-chemical parameters namely temperature, turbidity, pH, free chlorine residual (FCR), nitrate, fluoride and three bacteriological parameters: total coliform (TC), fecal coliform (FC) and fecal streptococci (FS) were analyzed. Temperature was average of 23.30, 21.23 and 22.57°C at the inlet, outlet and reservoir sampling points, respectively, which were above WHO and national standard limits of <15°C. Concerning FCR, at the outlet, FCR was 0.78 mg/l which was in the WHO recommended limit of 0.6-1 mg/L and at reservoir sampling point, the FCR was 0.35 mg/l which was in the WHO and national standard limit of 0.2-0.5 mg/L. The average concentration of TC, FC and FS at the inlet point was 196, 142 and 117 cfu/100 ml, respectively. On the other hand, at the outlet and reservoir sampling points, no indicator bacteria were found. In all pipe water samples, pH values were within the recommended limit (6.5-8). In the pipeline, 82.7 and 92.3% of sampling sites were found acceptable based on WHO and National standard for FC and FS counts, respectively. In household water container, 55.8 and 71.1% were in the acceptable limit of WHO and National standard for FC and FS, respectively. Pearson correlation analysis indicates that a significant positive correlation between TC/temperature (r = 0.809063) and a significant negative correlation exist between TC and FCR (r = -0.689336) in tap water samples. Using Pearson’s correlation coefficient, TC was found to be positively and significantly related to FC (r = 0.836887) and FS (r = 0.674766), FC was found to be positively and significantly correlated to FS (r = 0.84345) in household water.

Key words: Physico-chemical parameter, bacteriological quality, pipe water, household water, total coliform (TC), fecal coliform (FC), fecal streptococci (FS).