Sydney Desalination Plant at Kurnell won't reach full output for almost a year

Kogarah MP Chris Minns has blasted the Berejiklian state government for not taking more direct action on Sydney’s dwindling water storage levels.

Calls are mounting for Utilities Minister Don Harwin to bring forward water restrictions amid signs the $1.8 billion Sydney Desalination Plant won't reach full output for almost a year.

As Sydney closes in on its driest autumn and winter since 2006 during the depth of the Millennium Drought, the city's storages are at 65.3 per cent, down a quarter in 12 months.

On current rates of decline - 0.6 percentage points a week - the trigger point of 60 per cent for the Kurnell desalination plant to be activated could be passed months before it is fully operational after a tornado strike in 2015.

Mr Minns, the Labor water spokesman, pointed to comments Mr Harwin made a year ago today when dam levels were much higher.

"If the dams weren't full, we might need to do [the plant repairs] faster, but we don't need to, so it's good," Mr Harwin told Seven News.

Cordeaux Dam, south of Sydney, captured at 41.9 per cent full earlier this month; this time last year it was 93.8 per cent. Picture: Robert Peet

Cordeaux Dam, south of Sydney, captured at 41.9 per cent full earlier this month; this time last year it was 93.8 per cent. Picture: Robert Peet

Last September, Mr Harwin told state parliament it was unlikely the 60 per cent trigger "will be reached in the next five years".

The minister "has chronically underestimated the threat and risks of drought", Mr Minns said.

"Labor is demanding clarity on the water restrictions timetable."

A separate trigger point to supplement Sydney's storages has also failed.

According to the 2017 Metropolitan Water Plan, WaterNSW was to transfer water from the Tallowa Dam on the Shoalhaven River when Sydney Water levels dropped to 75 per cent full.

However, those transfers haven't happened because Tallowa's level itself was already too low when that point was crossed, WaterNSW said.

Larger supplies, though, were expected to come from the desal plant, which at full bore can meet about 15 per cent of Sydney's water use.

However, a drawn-out spat between the privately owned plant and insurers - after the tornado tore through the control room at the Kurnell site three years ago - has meant it can't even be turned on until this December.

DOWN: Total storage levels as at August 2 and same time last year. Source: WaterNSW

DOWN: Total storage levels as at August 2 and same time last year. Source: WaterNSW

"The testing phase is due to be completed by December 13," a spokesman for the plant said.

Drinking water would then take "four to five months" from the restart to be produced, and full production would only be reached "by month seven and eight", he said.

"If there's a hiccup or two in the plan, we do need to reconsider bringing the [stage one] water restrictions sooner," Stuart Khan, a professor at the University of NSW's School of Civil & Environmental Engineering, said.

"The nosedive [in water storage levels] is even steeper than going into the Millennium Drought."

The Kurnell plant has a contract that gives it eight months to get up to its full capacity of 250 million litres­ per day of water — or about 15 per cent of Sydney’s drinking water.

“It’s outrageous,” Mr Minns said, adding the Liberal government deal to privatise the desalination plant in 2012 was the “one of the most bizarre privatisation deals we have seen”.

Veolia operate the desalination plant at Kurnell under a 20-year contract and have up to eight months to restart the plant once instructed.

Veolia operate the desalination plant at Kurnell under a 20-year contract and have up to eight months to restart the plant once instructed.

Utilities Minister Don Harwin said "Greater Sydney’s water supply is robust and secure and we are confident that, despite the dry conditions, no homes or businesses will go without water".

Storages held enough water to supply the city’s population "for another two years - even without any rain at all over that period," he said, adding that authorities "have planned for drought conditions".

Determining how fast dam levels will drop hinges on water use, catchment rainfall and evaporation losses. At current rates, that 60 per cent level would be reached in about six months but at 0.8 percentage-point rate, it would be hit by early January - both before the desal plant will produce water.