A barge washed ashore at Alkimos in Monday night’s storm was towed back out to sea on Wednesday.

The support barge for the Alkimos desalination plant marine works was supposed to be 1km out to sea but broke free of its moorings.

A Water Corporation spokesperson said it was not damaged but could not say earlier in the week when the barge - the smaller of two being used - would be able to be towed out.

The barge is part of the Alkimos plan to provide Perth with an extra 50 billion litres of drinking water annually by 2028.

Crews spent Tuesday at Alkimos Beach stabilising the barge, with an excavator called in to help dig sand.

The barge was anchored down for Tuesday night.

The Water Corporation confirmed no one had been on board the vessel and there was no risk of a leak as no fuel was being carried.

People were urged to avoid the area while the recovery took place.