Rain 'isn't enough' to solve Auckland's water shortage crisis

Aucklanders are mistaken if they think the past week's rain means they'll be allowed to whip out the garden hose anytime soon.

The deluge only added 1 percent to the city's water storage levels, says Watercare chief executive Raveen Jaduram.

"We welcome the rain, but it isn't enough," Jaduram told The AM Show on Friday.

The lakes are now 43.4 percent full - they need to be up around 90 percent by the end of October, ahead of summer, if normality is to resume.

"The forecast from NIWA and MetService is we may have a dry spring," said Jaduram. "That is why the drought we are in is the most severe drought we've had. We're asking for savings." 

Aucklanders currently aren't allowed to use outdoor hoses and waterblasters, and are urged to cut use inside too. Jaduram himself says he's keeping his showers to four minutes.

"A four-minute shower will save 20 litres per person, per day. Dishwashers, washing machines, only use them when they're full. When you're brushing teeth, keep the tap off."

The drought is the most severe Auckland's had since the early 1990s. Since November, we've had only 452mm of rain - barely half the norm. Normally at this time of year the lakes are 76.8 percent full. Both the lake levels and rainfall are tracking below the drought of 1993/4. 

Watercare's target is for the city's water consumption to stay beneath 420 million litres a day - over the past seven days residents have been on target, using 416 million litres a day. 

A failure to keep it up, or continued lack of rain, will see restrictions tightened further, including the banning of watering sports fields.

There's limited capacity to take more from the Waikato River, which already supplies about a third of the city's needs. The treatment plant, capable of extracting 150 million litres a day, is already operating at near capacity.

"We are working with the Waikato Regional Council, Hamilton City Council and Waikato-Tainui to be able to take another 25 million litres a day - that would be the capacity of our treatment plant," said Jaduram. That expansion isn't expected to be completed until August 2020, Watercare documents show. 

More sources of water - such as at the Hickey Springs Bore in Pukekohe and Hays Creek, Papakura - will add about 11 million litres a day between them, but also won't be operational until later this year. 

Some of Auckland's water storage lakes.
Some of Auckland's water storage lakes. Photo credit: Watercare

Desalination - taking water from the ocean and making it drinkable - is a long-term option, but won't help ease the current drought.

"Right at the moment our big focus is this summer, and unfortunately a desalination plant won't be able to be built in the time we've got. But desalination plants would be an option for the future... The cost will be higher."