How water supply in parts of Delhi affected by Uttarakhand flash floods; know here

On Monday, the water supply in parts of New Delhi was affected, following high levels of pollution in the river Ganga river caused by flash floods in the state of Uttarakhand. After the disaster struck Uttarakhand’s Chamoli district on 7 February 2021, a large amount of debris and silt was washed down in the river and on Sunday it entered the Upper Ganga Canal which brings water to the national capital. Due to this, the water’s turbidity increased up to 8,000 NTU against the normal seasonal value of 100 NTU, according to an IE report. Turbidity is an indicator of suspended particles in the water. Officials of Delhi Jal Board (DJB) said the level of pollution decreased by Monday and Tuesday onwards, regulated water supply would be restored across the city.

According to the report, this recent disruption in water supply has again highlighted the growing water demand of the national capital and the struggle faced by authorities in meeting the demand. The river Ganga is a crucial surface water resource for the national capital and supplies approximately 240 million gallons per day (MGD) of raw water from the Upper Ganga Canal, which begins from Muradnagar in the state of Uttar Pradesh. It contributes nearly a quarter to Delhi’s supply of potable water.

In the early hours of Sunday, when turbidity levels rose, two treatment plants that supply water to south Delhi and east Delhi (at Sonia Vihar and Bhagirathi), had to reduce the capacity of their production by up to 20 per cent as their main source is the river Ganga. The DJB can treat nearly 1,000 NTU of water turbidity and sometimes even higher during monsoon seasons by adding coagulants in the water. However, officials said that when the pollution level increased up to 8,000 NTU, they had to wait for the quality of water to improve on its own. The Board’s water supply capacity to the city is around 925 MGD in total, which falls short of the average demand of approximately 1,200 MGD.

To increase raw water availability, at least three projects are in the pipeline with the Jal Board. One of the projects is reusing treated wastewater from the upcoming Coronation Pillar sewage treatment plant. This STP is likely to be constructed by the month of June this year. The plan involves wastewater treatment with advanced technologies in order to purify it above the discharge norms for STPs as well as release it into the river Yamuna close to Delhi’s northern border at Palla. From there, water would travel down the river for several kilometres, which would further purify it through natural processes, before being picked up at Wazirabad to be sent to treatment plants, adding nearly 70 MGD to the capacity of water production.

The report further said, another plan involves taking nearly 140 MGD water from UP in exchange for treated wastewater of equal amount from the national capital, which authorities in the neighbouring state can put to various use. The third plan, which is likely to augment the capacity of water by 130 MGD, has already been approved in the form of an MoU signed with the state government of Himachal Pradesh in December 2019, however, this water is yet to be received by Delhi as further discussions are underway at the Upper Yamuna River Board.

Additionally, the Board is undertaking projects for recharging the city’s groundwater, including water bodies’ revival as well as storing floodwater from the Yamuna in shallow reservoirs along the river. These projects are also expected to augment the Board’s capacity of water supply, the report added.