Sanitary risk assessment of domestic hand-dug wells in Yelwa-Tudu, Bauchi State of Nigeria

Abstract

The study investigated the sanitary conditions, as well as the water quality of 20 hand-dug in various households of Yelwa-Tudu community in Bauchi, Bauchi State, Nigeria. Yelwa-Tudu community was zoned into five areas and 20 hand-dug wells were randomly selected from the community, with 4 wells selected from each zone. Sanitary inspection format prescribed by the WHO was employed to assess sanitary condition of the wells. Water samples were taken from the 20 hand dug wells were assessed for bacteriological and physiochemical parameters. The bacteriological parameter tested for was total coliform count, while the physiochemical parameters were: colour, turbidity, temperature, pH, biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids, chromium (Cr⁺⁶), iron (Fe⁺²), manganese (Mn⁺²), lead (Pb), zinc (Zn), copper (Cu⁺²) and free residual chlorine (Cl). The wells were found to be at various levels of risk and all the samples from the private hand-dug wells tested positive to total coliform count. The physiochemical parameters of the well waters were compared with the guidelines set by the World Health Organization (WHO) and the Nigerian Standards for Drinking Water Quality (NSDWQ) and the chromium (Cr⁺⁶) and lead (Pb) levels were above the maximum permissible value. The study therefore recommends that hand-dug wells should be sited at a minimum recommended distance of 10 m away from latrines and other sources of pollution and the water quality standard should be enforced to improve the health of the community. It also recommends that knowledge about the method of sanitary risk assessment of hand-dug wells and other groundwater sources be disseminated and made known to the public.

Keywords: Sanitary risk assessment, hand-dug wells, groundwater, water quality, sanitation