Four Wyndham properties had their drinking water supply incorrectly connected to a recycled water main for up to a month in a City West Water (CWW) mishap.

The bungle happened when CWW began supplying class-A recycled water – the highest class of recycled water – to 4000 properties across west Wyndham in mid-November last year.

When a customer notified CWW of a change in water quality and taste, it was found that the property had an incorrect connection between the recycled water main and the drinking water supply.

A further three properties were also found to be incorrectly connected to the recycled water supply following CWW testing.

Of the four properties affected, two were in Wyndham Vale, the other two in Manor Lakes.

All connections have since been rectified.

A CWW spokeswoman said nine unoccupied display homes, inaccessible until this week, would also be tested.

There had been no serious health concerns from the mishap.

“Class-A recycled water is treated to a high standard so the likelihood of falling ill is low.”

However, impacted customers were advised to seek medical attention if they felt ill.

“CWW is working with the Department of Health and Human Services to assess any potential impact … The independent investigation is complete and we’ll be told findings soon.”