Evaluation of groundwater quality and its suitability for drinking purpose in Rajshahi City, Bangladesh Available to Purchase

A study was conducted to evaluate the hydrochemical processes controlling the water quality variations and to determine the water type of groundwater in Rajshahi City, Bangladesh, for drinking purposes. A total of 120 shallow and deep tubewell water samples were collected in pre- and post-monsoon seasons during the year 2008–2009 and analyzed for various physico-chemical parameters. The results of the analyses show that water samples were slightly alkaline to neutral pH. The average concentrations of Pb in all samples for the post-monsoon season were above the WHO's guideline for drinking water. For both seasons, arsenic levels exceeded the drinking water standard in 25% of groundwater samples and lead (Pb) levels exceeded in about 60% samples which contained elevated levels (>0.01 mg/L). The major cationic and anionic orders of dominance were unusual, being Ca²⁺ > Mg²⁺ > Na⁺ > K² > Fe³⁺ > Pb²⁺ > Zn²⁺ > Cu²⁺ > As (total) > Cd²⁺ and HCO₃⁻ > Cl⁻> SO₄²⁻ > NO₃⁻, respectively. The study reveals that the water type of the groundwater was calcium bicarbonate (Ca-HCO₃). Thus overall results suggest that groundwater quality of the study area was not suitable for drinking purposes without treatment especially for Pb and As.