Locals are being urged to switch off their sprinklers from today or risk getting slapped with a $100 fine.
The annual Winter Sprinkler Switch-off is a permanent water efficiency initiative that requires scheme and bore water users in Perth, Mandurah and parts of the South-West and Great Southern to turn off reticulation from June 1 to August 31.
Water Minister Dave Kelly said during the cooler months, lawns go dormant and plants do not require as much water, meaning it is the perfect time to save water for when we need it most.
"Winter is a really important time to help conserve water in preparation for warmer months when there is a greater reliance on sprinklers," he said.
"We know that by simply switching off garden irrigation we can collectively save five billion litres of precious water this winter alone."
Households are also encouraged to switch off reticulation not just in winter but also during periods of unseasonal rainfall.
The switch-off applies to both scheme and bore water users, however, hand watering is permitted and some exemptions may apply.
Water Corporation inspectors are out seven days a week monitoring for unauthorised sprinkler use during the switch-off period.
Anyone in the Winter Sprinkler Switch-off area spotted using their sprinklers between June 1 and August 31 risks a $100 fine.
In areas of the State not subject to the switch-off, normal watering rosters and daytime sprinkler bans still apply.
Since being introduced in 2010, the annual Winter Sprinkler Switch-off has saved around 50 billion litres of water - enough to fill Optus Stadium 50 times.