Quality characteristics of potable water from different sources of district Bannu (Pakistan) and their possible health impacts

The quality of potable water samples collected from 8 tube wells, 8 hand pu mps, 15 wells and 4 surface water sources in Bannu District were investigat ed and compared with international standards. It was observed that water fo rm wells and hand pumps seemed to be more polluted than those from other so urces due to high nitrite levels. Similarly the oxygen demanding content wa s higher in 88% hand pump, 60% wells and 25% surface water, whereas the mag nesium level was higher in almost all the samples. The synergetic effect of magnesium and sulphate concentrations has suggested that all hand pumps, 7 3% well water and the stream wats were unfit for drinking due to their laxa tive nature. It concludes that all hand pump water and 73% of all well wate r were not potable. The stream water was found to be laxative in nature due to higher concentration of both magnesium and sulphate. Na+, K+ and chlori de concentrations in all the samples were found to be within the permissibl e limits. The tube well water appeared to be comparatively safer, compared to other sources, due to lower COD and NO2- concentrations. Due to the pres ence of NO2-, 88% samples of well waters, 50% surface waters, 38% hand pump waters and only 13% tube well water were not potable. Overall, the water o f Bannu District has been found to be unsuitable for drinking purposes and are considered to be harmful to humans which may adversely affect the overa ll health of the people on prolonged usage of these substandard waters.