Assessment of pathogenic and nonpathogenic contaminants and their relative risks: the case of Dilla town water sources, Ethiopia

Abstract

The state of positive health and wellbeing is impossible without safe water. This study was aimed to assess the quality of Dilla town water sources. A total of 108 water samples were collected from twelve sites and selected physical and chemical parameters were analyzed. Most of the physicochemical parameters were in the acceptable range for water quality of WHO and CES. Three sampling sites were contaminated by nitrate with concentration range 51.68–126.30 mg/L. The heavy metal analysis indicated that the levels of iron, zinc, manganese, and chromium in some of the sites exceed values of WHO standard concentrations in the range 0.506–5.773, 3.606–4.312, 0.194–0.588 and 0.053–0.098 mg/L respectively. While three heavy metals (mercury, arsenic and lead) were above the WHO limit in all the sites. The bacteriological analysis of all the water sources indicated microbial contamination, total count of the coliforms ranging from 3 to 80 MPN/100 mL. As per WHO criteria, some of the water sources were grouped in to high-risk. The cause of such contamination may be due to no treatment or poor processing system. Therefore, the need to Hygiene promotion programs, urgent and continuous monitoring is highly recommended. HIGHLIGHTS Electrical conductivity in four sites and temperature in five sites were beyond the WHO guideline.; Highest nitrate level was determined in the water samples from untreated hand dug wells.; The level of arsenic, mercury, and lead in all the sites were above the WHO and CES limit for drinking water.; Microbial contamination was detected in all the water samples.;

Keywords

• contaminants
• drinking water
• health
• pathogen
• physicochemical