2. Groundwater Quality and Contaminations in India

India is the largest user of groundwater in the world (Saha et al., Clean and Sustainable Groundwater in India. Springer, 2017). The green revolution initiated in the 1960s has given an immense push for groundwater extraction through the installation of millions of irrigation wells around the country (Saha et al., Clean and Sustainable Groundwater in India. Springer, 2017). Besides, the domestic water supply in the rural and suburban areas is almost entirely dependent on underlying aquifers. The recent initiatives by the Government of India under the Jal Jeevan Mission, where it is promised that 24 × 7 pipe water supply will be available at the doorstep of every rural household, is immensely banking on groundwater (https://​jaljeevanmission​.​gov.​in/​about_​jjm#mission). Even in urban areas, traditionally it is believed to be dependent on surface water sources like dams or large-scale extraction from rivers. However, the rising demand for water from the rapidly expanding much exceeds the availability of the water from the present sources, thus gradually dependence on groundwater is increasing. Irrigation consumes more than 90% of total groundwater extraction. The value of groundwater used for irrigation is between 7.6 and 8.3 billion US$/year and the size of the groundwater-based economy is somewhere between 75 and 80 billion US$ (Shah et al., Hydrogeol J 20:995–1006, 2012).