Less than a kilometre from Delhi Jal Board’s Wazirabad Water Treatment Plant, Prema Devi, a migrant from Lakhimpur in Bihar, stands near the banks of Yamuna, ascertaining the direction of wind. With a broom in hand, Devi stares at weeds covering the blackish water of Yamuna, along with plastic bottles, broken pots and garlands. “Look at the water. It has turned completely dark in the last couple of weeks. People consider this water sacred. Is this how you treat a sacred object?” she says.
A dust-laden board urging visitors to not pollute the river stands a few metres away from the bank. Rajkumar, another Wazirabad resident, says, “No one pays any heed to such requests. For more than six days last week, there was no water supply because ammonia level in the river had increased and the plant had to be shut down. We were told industries in Haryana had released garbage in the river. We had to buy drinking water. We could not even use the water supplied through tankers. That water was yellow.”
With a monthly income of Rs 10,000, Rajkumar laments his family has to buy water every couple of months. “The water supply is affected for a few days every two months or so.”
Last week, DJB had to close down operations at two Water Treatment Plants (WTPs) — Wazirabad and Chandrawal — after it found high levels of ammonia in raw water supply from Yamuna. The measure hit water supply in various parts of the capital including Lutyens area which houses Parliament, Rashtrapati Bhavan and the Prime Minister’s Office. In all their years here, residents know water supply problems are due to “Haryana and UP”. Every few years, when effluents are released by NCR states, water supply in these areas in North East Delhi is affected.
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Standards are defined for drinking water based on two sources: ground water and surface water. The Central Pollution Control Board extrapolates these standards to different uses of water — class A water used for drinking water sources without conventional treatment but after disinfection; drinking water sources after treatment and disinfection — class C; water which can be used for bathing — class B; agriculture and industries — class E; propagation of wildlife and fisheries — class D.
For each of these, a few standard determinants are used to define the quality of water. These standards look at safety limits broadly in three areas — chemicals, bacteria and heavy metals in each source. The national standards under BIS defined in 1991 have been revised twice, and the latest 2012 standards introduced additional requirements: for ammonia, chloramines, barium, molybdenum, silver, nickel, and certain harmful byproducts of the disinfection process, like Trihalomethanes formed when ammonia combines with chlorine and Ammonical nitrogen compounds.
Studies specific to Delhi, and those tracing water pollution along the stretch of the Yamuna from different states have repeatedly found potable water in Delhi does not often meet safety standards. A 2006 study on arsenic in public water supply in Delhi by AIIMS found that in water samples from 42 areas, arsenic level was exceeding WHO/EPA permissible limit of 0.01 ppm (10 ppb). Another 2013 study by AIIMS found metals like zinc, cadmium and lead were high in tap water samples of Delhi.
A 2003 study by JNU found heavy metal concentration above safety limits in drinking water samples collected from areas near small scale industries. According to BIS and WHO standards, these metals are associated with different health effects. While aluminium is associated with neurological problems, copper impacts the liver and kidney, and arsenic and chromium are carcinogens. In 2012, the municipal corporation of Delhi’s public health wing, which conducted random tests on DJB water supplies from pipelines, found a high bacteria count in 81 out of 116 samples.
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