New Zealand / Infrastructure

Wellington Water's changes to limit water wastage this summer

08:31 am on 23 December 2024

Last year Wellington's water network was leaking like a sieve. Photo: RNZ / Samuel Rillstone

This time last year the Wellington region was in a seriously risky situation.

Wellington Water were warning the Hutt Valley, Porirua, and Wellington City that there was a serious risk of a water shortage.

It was not due to a particularly scorching summer or a major water main bursting that saw thousands of litres of water wash into the sea.

It was due to a water network that through decades of under investment had been leaking like a sieve meaning nearly half of the region's water was being lost.

The water shortage risk saw residents cut back their usage and flock to buy 200 litre tanks sold by councils - with demand causing a queue at Wellington City Council's tip shop.

Last year at one point there was a 70 percent chance of the region being plunged into level three restrictions which would have banned all outdoor residential water use and asked households to reduce indoor water use.

This year things are different, and the chances of the measures being put in place are 1 percent.

But how did they do it?

Wellington Water's director of regulatory services, Charles Barker told RNZ it started with fixing thousands of leaks throughout the year.

"By the time we get to this summer, we are looking at all of our councils will be into that sustainable level [of leaks] which is a phenomenal effort compared to where we were this time last year.

"In fact, there will actually be more, leaks on the private network, which is the house side of the network, that we know of, then there are on the public side."

The other major factor in the ease of water pressures this Summer was an upgrade to the Te Mārua Water Treatment Plant, Barker said.

Upper Hutt supplies 45 percent of the Wellington region's water.

RNZ reported in March an upgrade for the plant to increase the amount of water it can supply from 80 mega litres per day to 140 mega litres per day had blown out by more than $40 million.

The Te Mārua Water Treatment Plant upgrades have helped to ease the pressure on water supplies. Photo: Supplied

The first stage of that project is now complete and can add an additional 20 mega litres per day to the network.

This allowed the plant to pull more water out of their supply lakes, Barker said.

"To put that in context that's about another 10 percent of our total treatment capacity across the network, so that's a substantial influence."

The third element to Wellington Water's Summer turnaround was the watchful eye of Taumata Arowai.

In March, the water watchdog did not have confidence "acute water shortage risk" would be avoided this Summer - so they penned a letter to Wellington Water which asked them to come up with a plan to avoid it.

The organisations created a goal of reducing overall water demand (this includes water loss and water use) by 7.4 million litres per day by February next year which Wellington Water has been tracking to do.

Taumata Arowai's need to set targets was helpful, Barker said on reflection.

"Not just reduce but set some hard targets."

He told RNZ that they were not out of the woods yet regarding summer water shortages.

To provide long term certainty in the space they needed to focus on pipe renewals rather than fixing leaky pipes, he said.

"If you are fixing a panel on your car that's got rust there's only so many times you can cut a little bit of it out before its actually just more effective to replace the panel and that's where we need to be."

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