PETALING JAYA • Four water treatment plants in Malaysia's Selangor state were forced to shut down on Sunday after a diesel pollutant was detected in Sungai Selangor.

Millions of consumers in Klang Valley, where capital Kuala Lumpur is located, were affected by water cuts just two days after their water supply was disrupted from an odour pollution incident last Friday.

Water supply is expected to be fully restored in stages, beginning yesterday and lasting until Saturday.

"We are now waiting for the reservoir to be filled for water to be distributed from today and 30 per cent of the disrupted water is expected to be restored by 6pm," said Selangor Menteri Besar Amirudin Shari at a press conference yesterday.

Mr Amirudin said a possible act of sabotage was involved in the contamination of Sungai Selangor. He said a fuel tank cover on a sand dredging pontoon was found to have been pulled open, resulting in fuel flowing into the river.

"The pontoon has been at the location since 2013 but had not been operational the past two months," Mr Amirudin said.

"I have also asked for all the pontoons that are no longer in use to be removed from the river to prevent further risks," he added.

He said a police report was lodged by Selangor's sand mining concessionaire Kumpulan Semesta over the suspicion that foul play may have been involved.

Selangor police chief Noor Azam Jamaludin said at the same press conference that a police report was lodged on Sunday by the company that owned the pontoon. "Our investigations found two oil drums (on the pontoons) with the covers pulled off that resulted in 100 litres of diesel flowing into the river," he said.

Datuk Noor Azam also said workers at the site told police that three anglers were spotted fishing from the pontoon just before the incident. He added that the anglers initially refused to leave when told to do so.

"We are investigating whether the contamination was due to carelessness or an act of sabotage," he said.

The National Water Services Commission (Span) lodged a police report yesterday over the two incidents of pollution in Sungai Selangor that caused supply firm Syarikat Bekalan Air Selangor (Syabas) to shut down its major water treatment plants over the last few days.

Span chairman Charles Santiago said they hoped the police would investigate if there were elements of sabotage in both incidents. He added that it was a crime under Section 121 of the Water Services Industry Act 2006 to cause water to be contaminated.

A total of 1.2 million customer accounts in Kuala Lumpur, Petaling Jaya, Klang, Shah Alam, Kuala Selangor, Hulu Selangor, Gombak and Kuala Langat found their taps running dry last Friday following the detection of the odour pollution.

The same areas were also affected by the water cuts on Sunday.

The Rantau Panjang plant was shut down at 6pm on Sunday, while the Sungai Selangor phases 1, 2 and 3 water treatment plants were shut down between 8pm and 8.15pm, said Syabas, which is a member of the Air Selangor group.

By 3.30am yesterday, however, all four plants were back in operation, the water supplier said.

Air Selangor customer relationship and communication department head Abdul Raof Ahmad in a statement on Sunday night said Syabas had reported the contamination to the authorities and found that the pollution came from sand dredging works upstream.

The earlier shutdown was attributed to odour pollution traced to Sungai Liam, in the town of Batang Kali in Selangor.

THE STAR/ASIA NEWS NETWORK