Ammonia levels in the Yamuna at Wazirabad have climbed to 1.5-2 parts per million (ppm), above the 0.9 ppm threshold beyond which Delhi’s water supply operations begin to be affected.
The impact is felt particularly at the Wazirabad and Chandrawal water treatment plants, which draw raw water from the Yamuna. When ammonia levels rise, production is curtailed, and the DJB relies on alternative sources, including water delivered via the Munak canal, to dilute the polluted supply. NDMC has issued an advisory stating that water supply to areas fed by the Sonia Vihar plant may be affected. Normally, the Sonia Vihar water treatment plant draws raw water from the Upper Ganga Canal.
Dilution can help manage ammonia concentrations of up to around 2-2.5 ppm, officials said.
Still, operations on the canal were just restored after its annual maintenance period, an official said.
The spike comes as the city prepares for the Chhath festival. The local body has requested residents to cooperate and store additional water. A government official explained that water treatment at older plants relies on chlorination, and the supply is disrupted if ammonia levels exceed 1 ppm, which can form toxic chloramine compounds. The ozonation-based advanced plant helps us tackle pollution levels up to 4-5 ppm, which cover over 90% of such episodes. “We have started getting water from the Upper Ganga Canal after completion of its maintenance period, and sludge washing has been carried out over the last 24 hours.
the New Delhi Municipal Council, in a statement, said that due to a sudden increase in pollution levels in Yamuna raw water, water production at Sonia Vihar WTP has been curtailed, affecting water supply in its command area, including several NDMC areas While Delhi Jal Board has not issued any official advisory.
We will use Ganga water to dilute the raw water supply to minimise the impact,” a DJB official said.
