Comparative quality assessment of the drinkability of abandoned lake water with ground and municipal water in Raichur, Karnataka, India

Water sources across India have become scarce, resulting in the consideration of ground and surface water as a single resource. Potable water quality from the surface or ground must comply with the national regulatory limits. Eleven abandoned lakes, sixteen grounds, and five drinking water samples in the Raichur district were analyzed. Our findings of abandoned lake water included 14 physical-chemical parameters (mg/L): Total dissolved solids TDS(149.4–1298), Total hardness TH (77.31–401.31), Total alkalinity TA (89.44–430), Cl ⁻ (13.33–429.86), F ⁻ (0.16–0.89), Ca ²⁺ (26.98–121.03), Mg ²⁺ (12.23–68.1), SO ₄ ²⁻ (15.11–190.9), NO ₃ ⁻ (0.1–5.64), DO (38.3–60.12), COD (12.12–200.0), BOD (9.05–33.13) Free residual chlorine FRC(<1 mg/L) and pH (7.09–8.8). Groundwater: TDS (330.0–8724), TH(6.2–1518), TA(10–587mg/L), Cl ⁻ (25.27–366.0), F ⁻ (0.31–3.94), Ca ²⁺ (1.6–527.0), Mg ²⁺ (1.12–241.0), SO ₄ ²⁻ (7.56–440.0), NO ^3- (0.51–87.0) FRC(<1) and pH (6.96–7.9). Drinking water: TDS (36–891.67), TH(24.50–370.0), TA(18.89–340), Cl ⁻ (16.99–988.0), F ⁻ (0.09–1.83), Ca ²⁺ (12.83–136.8), Mg ²⁺ (2.83–56.59), SO ₄ ²⁻ (8.1–170.78), NO ₃ ^- (3.1–19.82) FRC(<1–80), and pH (7.05–7.47). Ninety percent of the abandoned lake water samples met the acceptable limits for parameters TDS, TH, TA, pH, Cl ⁻ , F ⁻ , Ca ²⁺ , SO ₄ ²⁻ , NO ₃ ^- , and Mg ²⁺ . The bacteriological quality of lake water samples showed coliform 30–210 total MPN/100 mL, and turbidity exceeded the acceptable limits (0–5 NTU). Sixty percent of the groundwater samples exceeded the permissible limits for TDS, 100% for magnesium, 75% for fluoride, 62.15% for calcium, and 40% for nitrate content. Five of the 16 groundwater samples analyzed for heavy metals showed an arsenic content of 0.094 mg/L. All the municipal water samples analyzed met the acceptable limits for physicochemical parameters and microbial load, indicating safe drinkability. This assessment outlines the future treatment needed for the restoration of abandoned lakes.