71 cities across India drew 18% of supply from groundwater
A survey of 71 cities across the country conducted by the Centre for Science and Environment (CSE) has shown that officially 82 per cent of all the water that municipalities of these cities supply comes from surface water resources, and the rest comes from groundwater resources.
But of these 71 cities, 11 depend almost completely on groundwater for public water supply. In the remaining, agencies supply water from surface sources by digging public tube wells.
“However, what is of particular concern is the connection between growing volumes of untreated sewage and contaminated groundwater. The circle of contamination is clearly what should worry city planners, as less and less sewage is treated even as more is generated. The groundwater comes under threat of contamination and public health is compromised,” the survey “Excreta Matters” warns.
In general, in a greater part of the country, groundwater is of good quality and suitable for drinking, agricultural or industrial purposes. There is salinity problem in the coastal tracts; high incidence of fluoride, arsenic, iron and heavy metals etc. in isolated pockets has also been reported, according to the Central Ground Water Board report 2010.
Inland salinity in groundwater is prevalent mainly in the arid and semi-arid regions of Rajasthan, Haryana, Punjab, Gujarat, Uttar Pradesh, Delhi, Andhra Pradesh, Maharashtra, Karnataka and Tamil Nadu. In some areas of Rajasthan and Gujarat, groundwater salinity is so high that the well water is directly used for salt manufacturing by solar evaporation.
The report itself claims that 85 per cent of rural population of the country uses groundwater for drinking and domestic purposes. Concentration of fluoride in groundwater beyond the permissible limit of 1.5 mg/l poses health problems. The presence of fluoride beyond the permissible limit has been observed based on the chemical analysis of water samples collected from groundwater the observation wells.
Arsenic in ground water is mainly in the intermediate aquifers up to a depth of 100m. The deeper aquifers are free from arsenic contamination. Apart from West Bengal, arsenic contamination in groundwater has been found in Bihar, Chhattisgarh, Uttar Pradesh & Assam.
High concentration of iron (>1.0 mg/l) in groundwater has been observed in more than 1.1 lakh habitations in 22 States and the Andaman and Nicobar Islands.
Nitrate, again, is a very common constituent in the groundwater, especially in shallow aquifers. The source is mainly from anthropogenic activities. High concentration of nitrate in water beyond the permissible limit of 45 mg/l causes health problems.
Oblivious to extraction
The survey has found a shocking fact: In the public domain, no one knows how much water is extracted. Every city today extracts more and more groundwater to meet its thirst. Water agencies formally indulge in extraction. Households do it privately, especially when the official pipeline fails to supply water to them. When water agencies hike water tariffs, commercial establishments quietly shift to the informal water economy, also predicated on groundwater extraction. The bottling water industry is thriving.
“Use of contaminated water is a serious public health issue as groundwater is used without any kind of treatment. It is contaminated with nitrates, heavy metals, and pesticides that can cause cancer, mental retardation. Pesticides enter the food chain through agricultures, hence it is important to protect the groundwater,” says Nitya Nacob, Programme Director (Water), CSE. It is lack of proper sewerage that adds to the problem as 78 per cent of sewage seeps back into the ground, he adds while drawing attention to the highly toxic discharges that are drained into rivers in industrial belts, which ultimately find their way into groundwater.
No piped water
Large areas do remain unserved by piped water. These have no option but to depend on groundwater. “We know that 80 per cent of water used in households, industries and institutions is discharged as waste,” the report points out.
The Central Ground Water Board monitors quality in their network of 15,600-odd wells countrywide. But the agency has no mandate to control pollution or to supply water. A city's public health and engineering department, or its water supply agency, does have the mandate to take into consideration the important matter of water quality. But since groundwater is not considered a critical part of the system, they do not monitor it. All in all, groundwater monitoring is neglected and this is part of the crisis of water supply in urban India, the CSE report points out.
The Central Pollution Control Board (CPCB) maintains 784 water quality monitoring stations, but mainly along river courses. Only 181 stations are “underground quality stations.” In these underground stations, contaminants — particularly pesticides — are not monitored regularly, but from time to time. By 2011, the number of monitoring stations had gone up to 1,700, of which 490 were for monitoring groundwater quality.
In 2007, the Central Pollution Control Board released a nationwide study on the status of groundwater quality. The survey collected 204 samples from some eight metropolitan cities in different parts of the country. Another 112 samples were taken from areas identified as a ‘problem' — industrial hotspots such as Durgapur in West Bengal or Vapi in Gujarat. It concluded: “There is a decline in the quality of this essential source slowly, but definitely.” In most cities, the survey found a toxic cocktail of bacterial and pesticide contamination.