“The earliest users will have their water supply restored is at midnight,” Air Selangor chief executive officer Suhaimi Kamaralzaman said in a press conference.

He said the Sungai Semenyih water treatment plant resumed operation this morning and the stabilisation of the water treatment process was ongoing.

It said the clean water would go through a quality test in accordance with the health ministry’s standard before supplying it to consumers.

He said the process of restoring water supply to the affected areas would be divided into three parts.

The water supply for the first group, consisting of 145 affected areas, will be fully restored by 6pm tomorrow; the second group (91 affected areas), by 6pm on Thursday; and the third group (38 affected areas), by 6pm on Friday.

The operations of the Sungai Semenyih and Bukit Tampoi water treatment plants were suspended on Sunday due to pollution.

This left more than 300,000 consumers without water for the second time in a month. Early last month, pollution in Sungai Gong had caused unscheduled water cuts for several days.

The suspension of the two plants saw Air Selangor unable to produce the daily 602 million litres of water required to be supplied to consumers in the Petaling, Hulu Langat, Kuala Langat and Sepang districts.