The Cheras Batu 11 water treatment plant, which resumed operations on March 30, was shut down at 3pm Monday after the ammonia content in the raw water rose to dangerous levels.

Syarikat Bekalan Air Selangor Sdn Bhd (Syabas) said the ammonia level was recorded at 4.50 part per million (ppm), exceeding the standard set by the Health Ministry.

Its Corporate Communications and Public Affairs assistant general manager Priscilla Alfred said Puncak Niaga (M) Sdn Bhd, operator of the water treatment plant, had been informed about the matter.

"With the temporary closure of Cheras Batu 11 plant, areas which receive water supply from the treatment plant face rationing as usual," she said in a statement.

Users have been urged to keep enough supply of water during rationing.

Syabas would continue to inform users on the status of the Cheras Batu 11 plant, depending on the condition of raw water.