KUALA LUMPUR - An Instagram post made by Datin Seri Masdiana Muhammad, the wife of Selangor Menteri Besar, has been slammed as tone-deaf by social media users.

Screenshots of the post, as reported by The Rakyat Post on Sunday (Sept 6), showed a photograph of a water tanker parked in front of a house with a hose running up the driveway. Another picture, captioned "When there's no water" showed her family swimming in their pool at home.

The post comes as millions of residents and businesses in Malaysia's Klang Valley were without water as a result of unscheduled water supply cuts. Water supply was cut in parts of Selangor and the capital Kuala Lumpur last Thursday after four water-treatment plants were shut down due to pollution.

When contacted by The Rakyat Post, Madam Masdiana apologised and promised to help other residents who have yet to receive water supply.

"As a mother, I just wanted to express my gratitude to the Air Selangor frontline staff who have been working hard for the past few days. It was not my intention to brag. As such, I apologise if such actions have created any misinterpretations and offended anybody," she told the news site.

Officials said the disruption was caused by pollution from a factory, with the water supply expected to be restored only after four days or more, The Star newspaper reported last Friday.

Selangor state and the federal territory of Kuala Lumpur are the most densely populated areas in Malaysia, with about seven million people.

Photos on social media showed thousands of people in many areas queuring to fill up pails and bottles from water tankers. Bottled drinking water flew off the shelves at supermarkets.

Water authority Air Selangor said that water restoration to Klang Valley users began on Saturday, with full restoration expected only by Wednesday, according to The Rakyat Post.

On Saturday, Malaysian authorities remanded for six days four factory managers who are suspected of involvement in the water pollution.

Media reports say the vehicle-maintenance factory allegedly poured used engine oil into drains that flowed into Sungai Gong, one of the rivers where its water is treated and later piped to homes, industries and offices.

Public anger boiled over after people learnt that the same company was fined RM60,000 (S$19,700) in March for the same offence.