Desalinated water currently provides the bulk of Perth’s drinking supplies.

Reports say that for the last financial year, just 7 per cent of Perth’s total water supply came from the Perth’s dams, while desalination contributed 47 per cent, and groundwater 46 per cent.

“While Perth no longer relies on stream flow into dams as a secure source of water, we still need to be mindful of our water use,” a Water Corporation spokesperson said.

But inflows have improved, with Perth’s drinking water dams now at 32.5 per cent capacity - 12 per cent more than the same time last year.

The Water Corporation said drinking water dams saw 34.1 billion litres of stream flow, about three times more than it did last year.

“Although this may seem like a lot of water, to put it into perspective, we supply more than 290 billion litres of drinking water a year to more than two million people connected to the Integrated Water Supply Scheme (IWSS) in Perth, the Goldfields and Agricultural Region and some parts of the South-West,” the spokesperson said.

It is an impressive improvement from last year’s stream flows, which were the lowest on record.

But these inflows to dams are still a long way below the post-1975 annual average of 189 billion litres.