Testing to begin on new 45 million litre Auckland reservoir

Some time in the early 2030s, Auckland's population will reach two million people - and the city's water agency wants to be prepared.

"Everyone tends to take it for granted," Watercare's Martin Hughes told 1News. "They open their tap and water comes out, but there's quite an involved process."

Hughes is overseeing upgrades at Auckland's largest water storage facility - which includes a new 45 million litre tank which should be up and running by early next year.

Over the last 12 months, Aucklanders used 423 million litres a day on average - the equivalent of about seven Olympic sized swimming pools every hour.

Around 80% of the city's water passes through the Totara Park complex every day, once it's been treated.

At capacity, the city's reservoirs can currently hold around 700 million litres.

Hughes said while population growth is part of the reason for the upgrade, disaster resilience is also front of mind.

"In the event we need to take one of the treatment plants out of commission, maybe because of a storm or a breakdown, these reservoirs are basically to provide a buffer."

Plans are already underway to build another reservoir of the same size in 2026. It means the facility will have around 200 million litres of storage space.

"That sounds like a lot, but it's probably only about 16 hours of water supply for the city," Hughes said.

It's one of around 170 Watercare projects currently underway.

The organisation plans to spend $13 billion on infrastructure upgrades over the next decade.

"We've got to invest in growth," said Watercare's Chief Infrastructure Officer, Steve Webster. "We need to invest in improving our service as well, improving our resilience like this project."

AUT infrastructure expert John Tookey believes water storage upgrades only go so far.

He said Aucklanders will need to become smarter about water use by recycling household wastewater, commonly known as grey water.

"In the future i would imagine we're going to start to develop various different housing solutions where a grey water tank is inherently incorporated into the build so that every house actually has this."