Evaluation of drinking water quality using heavy metal pollution indexing models in an agrarian, non-industrialised area of South-East Nigeria

The objectives of this study were to evaluate the physicochemical properties of drinking water sources at Ihiala, Nigeria, and to assess the water quality using the heavy metal pollution index, heavy metal evaluation index and contamination index models. Physicochemical parameters like pH, total hardness, total dissolved solids, nitrate, cyanide, residual chlorine and six metals (Al, Cd, Cr, Cu, Pb and Ni) were analyzed in the water samples, and heavy metal pollution indices computed. The spring and borehole waters had better organoleptic properties compared to stream, river and sachet waters. Total hardness, pH and nitrate were the major nonmetallic contributors to the poor water quality. The mean pollution indices were: heavy metal pollution index (HPI) 143.02 +/- 71.16, heavy metal evaluation index (HEI) 7.53 +/- 4.12 and contamination index (C-d) 1.53 +/- 4.12. Sixty percent of the samples exceeded the critical HPI value of 100. There was significant (P < 0.01) positive correlation between HPI and C-d, HPI and HEI (r = 0.886) and HEI and C-d(r = 1.000). Lead contributed most to heavy metal pollution of water in the region. The quality of most water sources in Ihiala is not good for drinking.