Urban Well Characteristics and Groundwater Pollution in Ibadan, Nigeria

Abstract

In many countries around the world including Nigeria, access to adequate potable water has become a mirage. The supply of pipe-borne water in Nigeria has, over the years, become grossly inadequate or totally non-existent. This has led many people to seek alternative sources of water, especially from hand-dug wells. Most of the hand-dug wells are frequently polluted due to improper location and human anthropogenic activities around the wells. This study was carried out to investigate the physical characteristics of the sampled wells in Ibadan city and their vulnerability to pollutants. A multi-stage sampling technique was used to sample862buildings (4%) of existing buildings (21,391) using wells in six Local Government Areas (LGAs) (Ibadan North, Ibadan North-West, Ibadan South-East, Ido, Egbeda and Ona-Ara) of Ibadan sampled. Microbial analyses were carried out on water samples collected using graph method from 50 wells that were randomly selected in the six LGAs. The study revealed that 97.8% of the wells were shallow; 90.4% were ringed and covered; 91.1% fetched manually from of the wells; 60.1% had no fixed drawer and allowed individuals to bring and use various drawers to fetch water; 8.9% of the wells provided mechanical device to fetch water; 29.9% relied on electricity generator; 41.5% relied on electricity provided by the Power Holding Company of Nigeria (PHCN); while 28.6% relied on both generator and PHCN.  About a half (47.8%) of the sampled wells were located down slope to the septic tank; 75.6% were situated at less than 25metres distance to septic facilities. Significant relationship was established between depth of the wells and groundwater pollution with bacterial count (t=17.230, p≤ 0.000); positive association exist between rings and bacterial count (t=10.209, p≤ 0.000); coliform count (t=-6.764, p≤ 0.000) and total suspended solid (t=-13.023, p≤ 0.000). The use of ring and cover on wells have been proved to be the best for proper hygiene while periodic water quality monitoring and incorporation of household water purification practices with hand-dug well water are recommended.