PETALING JAYA, Sept 7 — Some 1.2 million residents or 300,000 households throughout Petaling, Hulu Langat, Sepang and Kuala Langat districts will be affected by Semenyih water treatment plant’s shutdown at 1.40am this morning — due to contamination.

It is understood that the plant’s operation has been suspended due to contamination of Sungai Kembong, its fresh water source, by a nearby landfill.

In an immediate response, Syabas said that the Selangor river’s raw water was contaminated by leachate leaking from a breached dyke in the landfill.

The Leachate contains both dissolved and suspended material drained from the landfill.

“The plant was closed immediately upon detecting high content of ammonia in the water, at 6.41mg per litre, which is above the health safety standard of 1.5mg per litre, put into place by the health ministry.

“A yellow alert emergency plan has been into place. We are now trying to redistribute water from other treatment plants to the affected areas,” said Syabas chief executive officer Datuk Ruslan Hassan in a statement today.

Ruslan said that although it had prepared “32 water tankers and 300 water tanks” to supply water to the affected residents, not all residents may have access to the supply as the affected areas were “large.”

“However, since the areas affected are large, the capacity to deliver water may be limited,” he said.

The plant is operated by Konsortium ABASS Sdn Bhd, a state government subsidiary.

Ruslan said that Syabas was unable to determine when the treatment plant would resume operating because they have to clean the river water and repair the breached landfill’s wall.

"If the recovery process cannot be completed by this evening and the water level in the reservoirs continues to drop to the critical stage, Syabas will have to raise the Emergency Response Plan (ERP) to the red code," he said.

Following the activation of the yellow code, Syabas has set up 24-hour crisis operation centres in the four districts to undertake monitoring as well as to disseminate information to the affected residents.