Quantitative assessment of pollutants from man-made water wells for domestic supply in Temeke district, Dar es salaam

Access to adequate, clean and safe domestic water supply in major cities remains a challenge. To meet the current water demands, both shallow and deep wells are vigorously constructed. However the quality of abstracted water is still unknown. This study presents findings on quantitative assessment of pollutants from man-made water wells for domestic supply in Temeke district, Dar es Salaam. It was found that average groundwater temperatures were between 29.5°C and 36 °C, while waste water was 38 C which was above World Health Organization (WHO) permissible value. The pH values of water observed in agricultural, stress-free and residential shallow wells were below Tanzania Bureau of Standards (TBS) requirements for drinking water. Elevated amounts of organic pollutants 45617.04, 38.88 and 53.64 mg/L were measured in waste water, industrial and residential areas deep wells respectively. Water hardness, nitrate, contents of nitrite and ammonia were in conformity with WHO and TBS standards. Heavy metals and Total Suspended Solids were within allowed limits. Conversely, turbidity in deep wells from agricultural area was 7 Nephelometric Turbidity Units, NTU which was above WHO regulations. It was also revealed that total coliform and E. coli counts of deep wells were notably high. Total coliform in industrial waste water was much higher than in deep wells because of organic pollution. Henceforth the quality of water was found to be fairly acceptable for domestic use.