An unseasonably dry spring has seen Perth use billions of litres over its target amount, and with a hotter than average summer predicted households are being warned they need to cut back.

The latest statistics from the Water Corporation showed the Perth region was 8.7 billion litres over target since July 1.

Water Minister Mia Davies blamed high temperatures combined with low winter rainfall and the lowest inflows into Perth's dams on record.

With more than 40 per cent of household water used on gardens, Ms Davies said the Water Corporation was asking sprinkler times be shortened across the Perth region.

"We're asking residents to make sure that when they're putting their reticulation on, that they drop two minutes," she said.

"That will go a long way towards making sure we stay on target."

Last weekend more than one billion litres of water was used, and Ms Davies said that is an amount not normally seen until a very hot summer's day.

"You generally do see a spike in water use as the weather heats up," she said.

"This is a timely reminder for everyone to be careful with their water in what we have as a very dry climate."

Ms Davies said similar campaigns have worked well in the past.

"We all have a responsibility to manage this very precious resource and we're very confident the community will respond positively," she said.