Water quality evaluation of shallow wells in Kokrajhar Town of Assam, India

Kokrajhar town is the head quarter of Bodoland Territorial Area District (BTAD). This is one of the developing towns of western Assam. The town covers an area 8.24 sq km. There are ten wards in the town. The population of the town is 31972. The people of the town mainly depend on groundwater for drinking and their daily other needs. The major types of sources are ring well, tube well and few deep tube well. In this work, an attempt has been made to evaluate the water quality of 10 of the most-used shallow tube wells by monitoring the common quality parameters like temperature, pH, conductivity, total dissolved solids, hardness, bicarbonate, chloride, sulphate, phosphate, fluoride, common metals like Ca, Mg, Na, K, Fe and trace metals like As, Cd, Cu, Mn and Zn. The water is characterized by very high phosphate (0.08 to 0.22 mg/L) and iron content (0.2 to 1.1 mg/L) exceeding the maximum prescribed limit of World Health Organization in many cases. Many of the sources have Cd (0.039 to 0.142 mg/L) above WHO permissible limits. The study has shown important results indicating that even in an under-developed area, water quality problems exist. The results have been explained on the basis of known water-related problems associated with the people living in the area.