This article published on the International Water Management Institute (IWMI) site begins by highlighting the crucial role that groundwater plays as a decentralized source of drinking water for millions rural and urban families in India accounting for nearly 80 per cent of the rural domestic water needs, and 50 per cent of the urban water needs in the country. However, a variety of land and water-based human activities are causing pollution of this precious resource, informs the article. Its over-exploitation is causing aquifer contamination in certain instances, while in certain others its unscientific development with insufficient knowledge of groundwater flow dynamic and geo-hydrochemical processes has led to its mineralization.
The article goes on to provide information on the extent of groundwater pollution in the country and informs that the incidence of fluoride above permissible levels of 1.5ppm occurs in 14 Indian states, namely, Andhra Pradesh, Bihar, Gujarat, Haryana, Karnataka, Kerala, Madhya Pradesh, Maharashtra, Orissa, Punjab, Rajasthan, Tamil Nadu, Uttar Pradesh and West Bengal affecting a total of 69 districts.
High levels of salinity are reported from all these states except West Bengal and also the NCT of Delhi, and affects 73 districts and three blocks of Delhi. Iron content above permissible level of 0.3 ppm is found in 23 districts from 4 states, namely, Bihar, Rajasthan, Tripura and West Bengal and coastal Orissa and parts of Agartala valley in Tripura.
High levels of arsenic above the permissible levels of 50 parts per billion (ppb) are found in the alluvial plains of Ganges covering six districts of West Bengal. Presence of heavy metals in groundwater is found in 40 districts from 13 states, viz., Andhra Pradesh, Assam, Bihar, Haryana, Himachal Pradesh, Karnataka, Madhya Pradesh, Orissa, Punjab, Rajasthan, Tamil Nadu, Uttar Pradesh, West Bengal, and five blocks of Delhi. Non-point pollution caused by fertilizers and pesticides used in agriculture, often dispersed over large areas, is a great threat to fresh groundwater ecosystems.
Nitrate concentration is above the permissible level of 45 ppm in 11 states in India, covering 95 districts and two blocks of Delhi. Pollution of groundwater due to industrial effluents and municipal waste in water bodies is another major concern in many cities and industrial clusters in India.
However, is spite of this picture, there are no estimates available on the public health consequences of groundwater pollution as it involves methodological complexities and logistical problems. The paper argues that the use of technological measures to prevent the ill effects on human health can include methods such as demineralization using RO system, which can remove all hazardous impurities from drinking water and will be cost effective in many situations where TDS, nitrate and fluoride in groundwater are above permissible levels.
The cost of demineralization is falling rapidly. There are, however, challenges that water utilities would face such as building technical and managerial skills to design, install, operate and manage water treatment systems and also others such as making people pay for treated water and building knowledge and awareness among communities about groundwater quality issues and treatment measures.
The article argues that, in the long run, policies need to be focused on building scientific capabilities of line agencies concerned with WQM, water supplies, and pollution control; and restructuring them to perform WQM and enforcement of pollution control norms effectively and to enable them implement environmental management projects