As Sydney faces plunging dam levels and concerns around its desalination plant, one expert believes water restrictions should be brought in sooner rather than later.
The city's water storage fell to 65 per cent this week, down about a quarter since last year, as NSW continues to be gripped by drought.
Should Sydney's storage dip to 60 per cent, water supplies are supposed to be added from the $1.8 billion desalination plant. At current rates, this may occur within months.
But the plant is yet to recover from tornado damage three years ago. It cannot even be turned on until December with several more months needed to reach full production of drinking water.
This has prompted Professor Stuart Khan of UNSW's School of Civil and Environmental Engineering to suggest "level one" water restrictions be brought in at the 60 per cent threshold, instead of the demarcated 50 per cent trigger.
Level one water restrictions include limits on sprinklers, when garden hoses may be used and how vehicles are washed.
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"The rate of decline is extreme," Professor Khan told SBS News, adding the past six months was "one of the fastest declines" of the city's water supply he'd seen.
"We haven't even started summer," he said, a time when the city uses more water.
And the Bureau of Meteorology's latest climate outlook forecasts drier than average conditions across most of Australia during September and October, with temperatures expected to be warmer than usual.