Suitability and hydrogeochemical imprints of groundwater in residential location around Abeokuta, southwestern Nigeria

Water quality evaluations of domestic wells are required to monitor its consumption suitability since its dependence is on an increasing rate in the study region. Therefore, the rationale for the study is to obtain the hydrogeochemical characteristics of water from domestic wells and their level of potability. In the current study, the hydrogeochemical footprints of twenty water samples obtained from deep wells located in residential buildings were analyzed for TDS, Turbidity, TSS, TH, Acidity, Alka, HCO 3 − , CO 3 2- , DO, NO 2 − , NO 3 − , SiO 2 , PO 4 3- , SO 4 2- , Br − , Cl − , F − , Ca 2+ , Fe 2+ , Mg 2+ , K + , Na + , EC and ranked using the entropy-based water quality index (EBWQI) to determine its drinking suitability.Water classification was achieved using hydrogeochemical facies and the ion exchange was obtained using biplots of important water quality parameters. The mean concentration of the water quality parameters mentioned above were 717.69, 46.11, 157.20, 224.81, 72.91, 64.06, 78.07, 0.01, 3.89, 0.89, 51.56, 16.50, 0.73, 32.87, 0.01, 174.41, 1.89, 58.91, 0.03, 19.41, 3.05, 72.82 mg/L and 1009.63 μS/cm, respectively. Benchmarking the results with the WHO 2017 standard, 10%, 85%, 10%, 45%, 20%, and 45% of the water samples surpassed the threshold for TDS, EC, DO, NO 3 − , Cl − , and F − , respectively. The groundwater classification derived from the piper plot revealed 40% mixed type, 15% Na-Ca-Cl water type, 15% Na-Ca-Mg-Cl water type, 20% Ca-Na-Cl water type, and 10% Ca-Na-Mg-Cl water type, with Na and Cl dominating the hydrogeochemical facies. The geochemical activity governing the groundwater chemistry obtained from the plot of [Ca 2+ + Mg 2+ ] vs [HCO 3 − + SO 4 2− ] showed silicate weathering and carbonate weathering in 5% and 95% of the water samples, respectively. Furthermore, the ion exchange activity based on [Na + + K + – Cl − ] vs [(Ca 2+ + Mg 2+ ) – (HCO 3 − + SO 4 2– )], CAI-1 and CAI-2 plots supports reverse ion exchange. Generally, the chemical activities support rock-water and evaporation dominance within the sample location. The EBWQI ranking showed that 10% of the water samples are excellent, 20% are good, 40% are moderate, 10% are poor, and 20% of the water samples are abysmal for consumption. Therefore, the water situation in the study region requires adequate treatment strategies to foster healthy living for residents.