Investigation of Possible Groundwater Contamination from Septic System Siting in Port Harcourt, Nigeria

Abstract

The purpose of this study was to investigate the effect of siting of septic systems on the quality of groundwater in the immediate vicinity. Water samples were collected randomly from twenty (20) boreholes located less than 30m from septic systems in Port Harcourt, Nigeria to determine their physico-chemical qualities and microbiological characteristics. Standard analytical techniques were employed in the investigation. Five (5) boreholes at distances ranging from 60m to 100m from the nearest septic system were sampled for analyses as controls.  The water temperature, dissolved oxygen, turbidity and total dissolved solid values were within the World Health Organisation (WHO) standards. The pH of water from all the boreholes including the controls were lower than the WHO standards.  The values of the physico-chemical parameters obtained for water samples from boreholes located less than 30m were similar to the values obtained from control boreholes.  These physico-chemical parameters were invariably not a function of the location of the borehole in relation to septic system. The total coliform bacteria concentration ranged from 130 MPN index/100ml to 172 MPN index/100ml while the faecal coliform distribution ranged from 14 MPN index/100ml to 36 MPN index/100ml. Going by WHO standards on total and faecal coliforms, the studied boreholes and controls are all polluted. However, total Coliform and faecal coliform are found in all the control boreholes. The presence of these coliforms in borehole located close to septic systems cannot be specifically said to have come from the septic system.

Keywords: Borehole, septic system, advection, dispersion, diffusion, coliform, contamination.