However, tests at the Bukit Tampoi plant still detected odour pollution, although it has dropped significantly from a threshold odour number (TON) of 9 at 6.30pm yesterday to 2 at 6am today.

Air Selangor corporate communication head Elina Baseri said tests at the Sungai Semenyih plant recorded TON readings of 0 three times in a row this morning.

It will take some 12 hours before the plant can resume supplying water to users again, as works to treat the raw water and stabilise the plant’s system are ongoing.

“The Sungai Semenyih plant has resumed operating its raw water pump this morning for the clean-up of raw water pipes and water treatment tanks.

“The water supply that will be distributed will go through water quality tests to ensure compliance with health ministry standards,” she said in a statement.

Elina said the water supply from the Sungai Semenyih plant will be restored in stages according to location, adding that Air Selangor will release a schedule for these areas that are supplied by the plant.