Quality of surface and ground waters for domestic and irrigation purposes in CKD/CKDu prevalent areas in Moneragala District, Sri Lanka

Total of 152 water samples from CKD/CKDu endemic areas and 30 water samples from non-CKDu prevalent areas in the Moneragala District were collected separately. pH values of water samples varied from 5.04 to 8.37 which are within the permissible limit prescribed by World Health Organization. More than 15% of water samples showed low Dissolved Oxygen (DO) values indicating heavy contamination by organic matter. Electrical conductivity was high ranging between 32 and 2865 μS/cm indicating higher mineralization in groundwater. The major ion chemistry reveals that the array of abundance of cations was variable as Na+ > Ca2+ > Mg2+ > K+ in dug wells, Ca2+ > Na+ > Mg2+ > K2+ in tube wells and Ca2+> Na+ > K+> Mg2+ in surface waters, while anions varied as HCO3->Cl->SO42->F- in water samples in both seasons. Computed WQI, 43%, 33%, and 82% for dug wells, tube wells and surface water respectively were in good water quality in this area, while waters in 30% and 25% of dug and tube wells respectively exceeded the value of 100 showing not suitable category. Considering irrigation quality, 88%, 93% and 96% of dug, tube and surface waters respectively were less than the permissible level. SAR values in the study area ranged from 0.08 to 4.91 meq/L by showing no danger of sodium as per SAR. The bulk of studied waters are appropriate for irrigation according to Residual Sodium Carbonate (RSC). Considering KR and PI, majority of water samples of the study area are suitable for irrigation purposes