WHAT WE DRINK IS IT SAFE? AN ASSESSMENT OF DRINKING WATER IN KOCH BIHAR DISTRICT, WEST BENGAL

The groundwater quality of Koch Bihar District (West Bengal, India) has been assessed to determine the suitability of groundwater for drinking. Eight parameters have been taken into account for calculating the water quality index (WQI): pH, total hardness (TH), magnesium (Mg), calcium (Ca), carbonate (CO₃^2-) and bicarbonate (HCO₃^-), chloride (Cl), iron (Fe) and sulfate (SO4^2-). Secondary data on water quality were collected from Central Ground Water Commission (2018), and the samples of water have been collected from the various locations and analyzed accordingly. The physico-chemical data were evaluated following the standards of BIS and WHO guidelines. The calculated WQI ranges from 23.62 to 95.12. In terms of groundwater quality for drinking purposes, Tufanganj-1 and Koch Bihar-1 seem to be the worst blocks. The magnesium (Mg) concentration exceeds the acceptable limit of 30 mg/l in Mathabhanga I, Mathabhanga II, Koch Bihar II, Dinhata II, and Sitai Block and Koch Bihar II exceeds its permissible limit (100mg/ l). The Iron (Fe) value exceeds the acceptable limit of 0.5 mg/l in Koch Bihar II. The Total Hardness (TH) value exceeds the acceptable limit (200 mg/l) in Mekhliganj, Mathabhanga-I, Koch Bihar-I, Koch Bihar-II, Tufanganj II, Dinhata II, Sitai. However, no sample crosses the maximum acceptable limit for pH, carbonate, chloride, and sulfate. It is suggested that water drawn from such sources be disinfected adequately before being used for drinking or other domestic purposes.