This is because 80% of Penang’s tap water is sourced from Sungai Muda, which is connected to two other rivers, Kupang and Ketil, in Baling.

The flood resulted in muddy waters, reaching turbidity levels of 3,000NTUs, which is categorised as “extraordinary”. A 1,000NTU level is considered normal.

Late last night, Kedah shuttered three of its main water treatment plants along its side of Sungai Muda, affecting 201,000 account holders in the Kulim Hi-Tech area and Sungai Petani.

Menteri besar Sanusi Md Nor said the turbidity of Sungai Muda forced the state water company to close all plants between 10.50pm and 11.10pm.

The Penang Water Supply Corporation (PBAPP) followed suit, shutting down its main Sungai Dua, Butterworth, treatment plant at 8am after finding water quality levels dropping below minimum standards set by the health ministry.

PBAPP CEO Jaseni Maidinsa said reserves from the Mengkuang dam had been released to offset the water shortage and dilute the turbid waters at Sungai Dua.

He said the Sungai Dua treatment plant was gradually reopened four hours later at noon after the water quality improved.

“We have received queries and complaints. We apologise for the inconvenience, as this is beyond our control.

“We expect normal water pressure to be restored by noon tomorrow (Thursday),” he said in a statement.