The implementation of the first and third stages of the water rationing plan in Selangor will continue as scheduled until Syarikat Bekalan Air Selangor (Syabas) receives instructions from the Selangor government and the National Water Services Commission (Span).

Syabas' corporate Communications and Public Affairs Department assistant general manager Priscilla Alfred said although the water treatment plants at Cheras Batu 11 and Bukit Tampoi had resumed operation since March 17 and 19 respectively, the company was unable to ensure the stability of the ammonia level.

"The ammonia level is still under the supervision of the operator of the water treatment plants. Syabas has been informed that the water treatment plants will be operational according to the quality of the raw water," she said in a statement on Friday.

Alfred said rainfall in some areas, including around Sungai Selangor area over the past few days has increased water flow in the river.

However, the release of water from Sungai Selangor dam remains at the reduced level of 500 million litres per day.

She said the wet weather allowed Sungai Selangor Phase 1, Sungai Selangor Phase 2, Sungai Selangor Phase 3, Sungai Rasa and Rantau Panjang water treatment plants to increase the production of treated water.

The first stage of water rationing plan involved several areas in Hulu Langat, Kuala Langat and Sepang was caused by the closure of Cheras Batu 11 and Bukit Tampoi water treatment plants due to ammonia contamination.

The third stage water rationing plan involved several areas in Gombak, Petaling, Kuala Lumpur, Kuala Selangor, Hulu Selangor, Klang and Shah Alam was due to lack of treated water supply.

Syabas hopes that consumers use water wisely so that the existing water supply can last long.