A day after the Delhi Jal Board (DJB) was forced to shut two water treatment plants, ammonia levels in Yamuna river water came down slightly, but not enough to restart the plants.
On Tuesday evening, the ammonia level came down to 1.0 PPM, whereas the minimum treatable level is 0.6 PPM. The pollution level has decreased considerably upstream of Wazirabad.
According to DJB officials, the water supply will normalise only by Wednesday evening.
Water supply in north, central, west and south Delhi was affected on Tuesday after the water treatment plants at Wazirabad and Chandrawal were shut down on Monday afternoon.
Tanker service wasn't available either because of scarcity of treated water.
"We have started the cleansing operation and 900 cusec of water is being flushed out. By night, the ammonia level is expected to be within the permissible limits and water supply is likely to resume by Wednesday evening," RK Garg, member, water works, DJB.
The rise in ammonia levels was attributed to the increase in pollutants being released in the Yamuna at Panipat. This is the second time in the last three months that the plants were shut down owing to high pollutants in the water.
"The matter has been taken up with Haryana several times in the past through the Central Pollution Control Board. An effective response is expected from them so that this doesn't happen again," said DJB chief executive officer, Ramesh Negi.