The aquifers of Delhi stand at huge risk. The reason: Contaminated surface water. Sewage water from drains, toxins from illegal RO water plants, or even polluted water from Yamuna will, if not checked, contaminate all underground potable water.
A water body works as a soak pit, and the contaminants present in the water reach aquifers through them. It can play havoc with Delhi’s groundwater in future — and that future is not too far!
Contaminated water from illegal RO water plants in the city are a major threat. Such plants, on one hand, extract underground water from a tubewell and, on the other, discharge the contaminated and toxic water into the ground through a parallel tubewell.
Arvind Rudra, environment quality management consultant, green growth trainer (UNESCAP, AIT Thailand), says, “The unauthorised drinking-water factories in urban areas in Delhi-NCR draw out groundwater at 500-1000 TDS (Total Dissolved Solids), extract drinking water from it at 50-100 TDS, and reject the remaining water with 3,000-4,000 TDS. Such water includes toxins, such as heavy metals and fluorides, and other inorganic salts along with suspended solids. So, the entire water becomes unfit for human consumption.”
There’s also sewage discharge to be taken into account.
In Delhi, there are several water bodies under the DDA and the DJB. Unfortunately, dirty sewer water from nearby colonies is discharged into them. Though the civic agencies have put up boards to warn residents against doing so, but who cares!
According to the activists, neither the DDA nor the DJB is serious about the matter. These water bodies are shown as revived, but that’s just on paper — the reality is far from it. One such water body can be found at Bamnoli Village in Sector 28, Dwarka.
Assistant professor of geology, Delhi University, Dr Shashank Shekhar, says, “Diversion of sewage and other wastes to unlined water bodies often lead to contamination of in situ aquifers. The extent of that contamination will, of course, depend on the local hydro-geological system.”
Independent water expert Nitya Jacob says, “The DJB has tubewells at Palla in the Yamuna floodplains to draw water. However, excess drawing will eventually result in polluted water from Yamuna entering this aquifer. So polluted surface water at one place can pollute the aquifer at another place, and it depends on the nature of the aquifer and the local hydro-geological system.”
Environment activist Diwan Singh, who has been working on the water bodies in Delhi, further adds, “There are more than 600 water bodies in Delhi, but hardly any of them are functional. In spite of judicial orders — both by the High Court and the NGT — no work has been done to revive them. In 2012, we surveyed 50 villages — many of them in Dwarka and Najafgarh — and we found that of the 183 water bodies, 93 were dry and 63 had sewage in them. Even today, the condition remains largely the same. Sewage going into the water bodies is an environmental hazard as it contaminates the groundwater. But the authorities, of course, are not bothered as water bodies do not make for popular electoral issues.”
Professor SC Rai from department of Geography, Delhi University, explains, “One of the serious anthropogenic impacts on groundwater is pollution. In fact, the problem of groundwater contamination is more widespread than its overuse and depletion. There are various sorts of contamination — from human waste, non-degradable organic materials, organic and inorganic chemicals, oil and its byproducts and heavy metals.”
Rai adds, “Landfills and dumps are also a source of contamination. Leaking septic tanks and sewers and even chemical nutrients for plants have contaminated groundwater in urban and suburban parts of Delhi. Lack of sewage treatment plants is another problem. Hence, most of the drains in Delhi are a source of groundwater contamination.”
According to findings by Central Ground Water Board, the extent of fluoride contamination in groundwater is quite high in the western part of Delhi — in north-west, south-west and the west districts. Of the nine districts of Delhi, seven are over-exploited. Nitrate concentration in groundwater is found mostly in areas where domestic effluent is discharged into open unlined drains.
Dr Gopal Krishna, director of Toxics Watch Alliance (TWA), an Indian portal for environmental news, says, “In the Yamuna floodplains, arsenic has been found in excess of the permissible limit of 0.05 mg/litre, as prescribed by the Bureau of Indian Standards. Samples have been collected from a hand pump in Geeta Colony and three hand pumps in Nagla Rajpura near Mayur Vihar Phase I on the eastern bank of Yamuna. The tests for groundwater from the existing wells of the Najafgarh have revealed increasing pollution on quality parameters such as bicarbonate, calcium, chloride, electrical conductivity (EC), magnesium, nitrate, sodium, and sulphate.”
Activists and experts have repeatedly said that the DDA has turned a blind eye to toxic chemicals being released by the industries and malls across the city. According to them, Vasant Kunj malls have been contaminating the groundwater in the Delhi Ridge (tail end of the Aravalli Hills) and the Aravalli Biodiversity Park, spread across 692 acres.
“It (DDA) is indifferent towards gallons of sewage water flowing out of commercial establishments and residential areas into the park. The aquifers of the Ridge have the purest form of rainwater. Sewage water is poisoning that pristine water. In 2012, the Delhi High Court noted that the DDA has been mixing raw tubewell water into the DJB water unmindful of the fact that the groundwater is highly saline and contaminated. There’s need for statutory regulation of groundwater — and fixing of accountability,” asserts Dr Krishna
