Public health and environment committee chairman Jamaliah Jamaluddin said investigations on July 6 and July 8 by Luas, the state’s water management authority, showed that a plastic recycling facility had probably been discharging effluent directly into the river through an unauthorised pump.

A separate factory storing blue-coloured rubber liquid used in glove manufacturing was also found responsible as a leaking tank outlet allowed chemical waste to flow from its compound into a nearby drain, reaching the river.

These two factories were also found to be extracting river water without approval.

“Luas immediately issued an order to these factories to stop discharging waste, and to clean up the river,” Jamaliah said in a statement.

Samples from both locations have been sent to the chemistry department for further analysis, and the cleanup of the river was completed at about 10.45pm on July 8.

Luas is investigating the two factories for polluting water sources and unauthorised water extraction.

“The Selangor government views water pollution issues seriously, whether or not they affect raw water supply to treatment plants,” Jamaliah said.