Selangor CID chief Fadzil Ahmat said the two company directors, a father and son aged 62 and 31 respectively, were detained in Rawang at 11.30am today.

The six workers detained were two local men and four migrants from Nepal, Pakistan and Myanmar.

He said investigators traced the odour to Sungai Gong, a tributary of Sungai Selangor in Rawang.

The source of the pollution is believed to be a company which repairs and sells construction machinery.

“All the suspects will be remanded tomorrow at the Selayang Court.

“Investigations are being conducted under Section 430 of the Penal Code,” he said in a statement today.

This section deals with “mischief by injury to works of irrigation or by wrongfully diverting water”.

Nearly 1.2 million Air Selangor households in the Klang Valley experienced unscheduled water supply disruptions on Monday after four Sungai Selangor water treatment plants were shut down due to contamination of raw water sources.

Early last month, another pollution incident in Sungai Gong had caused unscheduled water cuts for several days, affecting 1.2 million households in 1,292 areas in the Klang Valley.