Hydrogeochemical controlling variables for the high rate of groundwater contamination in a shallow hard rock aquifer of the semi-arid region of Medchal District, Telangana State, South India, and its associated health risk to children and adults were studied in detail. A total of 56 groundwater samples were analysed for major ion chemistry in pre- and post-monsoon seasons in 2019 year. Spatial distribution, hydrochemical facies, water–rock interaction, health risk assessment, carcinogenic risk, and principal component analyses were carried out to assess the water quality. Spatial distribution of nitrate and fluoride concentrations, high values were observed in the northern, southern, central, and south-western parts of the region. In terms of NO3−, about 88% and 63% and for F− 45% and 32% of the groundwater samples are non-acceptable limits of nitrate 45 mg/l and fluoride 1.5 mg/l during pre- and post-monsoon seasons, respectively. Modified Gibb’s plot showed the majority of the area is dominated by rock dominance and evaporation mechanisms. Statistical analysis reveals that water chemistry is governed by weathering of feldspar minerals and the cation exchange reaction mechanism. The petro-graphical studies revealed the dominance of plagioclase, orthoclase, quartz, biotite, apatite, and hornblende minerals in the host rock. The factor analysis results reveal that the geogenic and anthropogenic activities contribute to groundwater chemistry. Health risk assessment was carried out by calculating the hazard quotient (HQ) on the basis of intake exposure of groundwater, as per the USEPA. Results were obtained for total hazard index value greater than 1 for adults and children, which causes non-cancerous health effects.

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Valuation of groundwater chemistry and its related health hazards risk for humans is a prerequisite remedial measure for human health. The semi-urban region in southern India was selected to measure the groundwater quality and interpret the human health risk valuation with deference to different age groups of adults and children through oral intake and skin contact of elevated concentration of fluoride (F -) and nitrate (NO3 -) water in the absence of other alternatives. Water samples were collected from the semi-urban region for pre and post rainfall period and resolute its chemistry. However, Fconcentration ranges 0.28 -to 5.48 mgLand 0.21 -4.43 mgL -; and NO3concentration ranges 0.09 -to 897.28 mgLand 0.0 -to 606.10 mgLelevating the drinking standars of Fin 32% and 38% samples and of NO3in 62% and 38% during pre and post rainfall seasons respectively. The fluoridebearing minerals are the main sources of elevated concentration of Fand excessive use of nitrate fertilizers as the chief source of NO3concentration in the aquifer regime. Water Quality Index (WQI) ranged from 18.3-233 and 12.97-219.14; 20% and 22% showed poor water quality for pre and post rainfall seasons with WQI = >200. Piper plot suggests that 46% and 51% of samples signify carbonate water type (Ca 2+ -HCO 3  ), and 32% and 28% of groundwater samples show Ca 2+ + Na + + HCO3type water for pre and post rainfall seasons respectively. Gibb's plot suggests the dominance of water-rock interaction in the aquifer system. Further, the principal component analysis (PCA) supported the same factors contributing to the elevated concentration of Fand NO3in groundwater. The hazard quotient (HQ) through ingestion (HQing) and dermal (HQder) pathways of Fand NO3was observed higher than its acceptable limit of 1.0 for different age groups indicating the non-carcinogenic effect on human health and effective strategic measures to be implemented in the area for improvement of human health conditions.

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Groundwater is a major valuable asset, which helps to sustain human ecology, particularly in crystalline terrains. Hence, proper quality monitoring of groundwater is a crucial task in understanding its suitability for drinking water and irrigation water practices. For this, fifty groundwater samples were taken and evaluated for physical, chemical characteristics and major ions during in pre and post-monsoon seasons. The results obtained were compared with IS 10500 standard which shows more than 80% of the samples in both seasons were unfit for drinking. The obtained results were checked to know the irrigation suitability. It is found that most of the samples (80%) were fit for agricultural practices in both seasons. The major water facies were CaCl, mixed CaMgCl and NaCl water types in pre and post-monsoon seasons. The spatial distribution diagrams of the major ions were high concentration in Northern areas followed by Western and South-Western portions. As per the groundwater quality of pollution index (GQPI), most of the study region (62 percent) comes under the low contamination zone and the rest (38 percent) under the moderate to unacceptable zone in drinking water specifications. Factor analysis reveals that the study region which predominant of weathering of silicate minerals, ion exchange and anthropogenic inputs of major contamination of groundwater quality.