POTABILITY OF WATER SOURCES IN RELATION TO METAL AND BACTERIAL-CONTAMINATION IN SOME NORTHERN AND NORTH-EASTERN DISTRICTS OF INDIA

A total of 1094 water samples from 326 springs, 207 streams, 183 dug w ells, 151 piped supplies, 90 tube wells, 75 hand pumps, 60 rivers and 2 lakes were collected from eight northern and six north-eastern distr icts of India. Samples were analysed to assess their potability by est imating the level of heavy metals and bacterial (coliform and faecal c oliform) contaminations. Iron was found in a maximum number (53%) of w ater samples from hand pumps, followed by lead in 43% of the tube well s, chromium in 16% of dug wells, cadmium in 13% of streams and mangane se in 7% of hand pumps above their maximum admissible concentrations ( MACs). Maximum metal pollution has been observed in a considerable num ber of water samples from Doda, followed by Almora, Mirzapur and Banku ra. Hand pump water samples exhibited maximum metal pollution followed by dug well, spring, stream and river water samples. Contamination of coliform and/or faecal coliform bacteria ranged between 41% and 67% o f water samples from open water sources but it was also less, i.e. 6-1 5% of water samples from tube wells and hand pumps. In general, 42-85% of water samples from districts surveyed, except from Jammu (18%) and Mirzapur (27%), were found to be bacteriologically unsatisfactory. Si nce toxic metals and pathogenic bacteria pose a risk to public health, monitoring of drinking water sources is required.