Groundwater is one of the most important natural resources in India and plays a vital role in maintaining the country’s water security. It is the water present below the Earth’s surface in the pores and cracks of soil and rocks. Groundwater is replenished mainly through the infiltration of rainwater and surface water into the soil. In India, where rainfall is highly seasonal and unevenly distributed, groundwater acts as an essential source of water for agriculture, domestic consumption, industries and ecosystems. From the perspective of environmental chemistry, groundwater is also an important component of the hydrological cycle and interacts continuously with soil, rocks, minerals and pollutants. Groundwater is particularly important for Indian agriculture. A large proportion of irrigated agricultural land depends on wells, tube wells and bore wells. During the dry season and periods of inadequate rainfall, groundwater provides a relatively reliable source of irrigation. The development of groundwater irrigation has helped increase agricultural production and supported food security, especially in regions such as Punjab, Haryana, Uttar Pradesh, Rajasthan and parts of Bihar and Gujarat. It also allows farmers to obtain water when rivers, ponds and other surface-water sources become inadequate. Groundwater is equally important for domestic water supply. In many rural areas, households depend on hand pumps, dug wells and tube wells for drinking, cooking, washing and sanitation. In several towns and cities, groundwater contributes significantly to municipal water supplies. Its availability close to the place of use reduces the need for extensive water transportation and infrastructure. Groundwater