He said the authorities were still investigating the sources of pollution, adding it could have originated from a nearby industrial estate.

“State and federal authorities are working closely to identify the actual source of pollution.

“As of yesterday (Monday), we are still unable to locate it … of course, we apologise for what happened.

“We need to ensure stringent monitoring (at water treatment plants) and we must penalise the culprits … it affects people’s lives.

“We must make sure those responsible are punished. We cannot tolerate this happening every time,” he told reporters here today.

Earlier, Maximus witnessed the signing of a sale and purchase agreement between Ranhill Holding Bhd and SIIC Environment Holdings Ltd here today.

The Semenyih water treatment plant was shut down a few times following odour pollution.

Investigations into the cause of the contamination are still under way.

The authorities first detected contamination on Sept 22 and an investigation was initiated.

The affected areas include Hulu Langat, Kuala Langat, Sepang and Petaling.

It was reported that the contamination could have come from Sungai Lalang at the Hi-Tech Industrial Park, Semenyih.