Capital has 1% chance of severe summer water restrictions with 20m litres more a day treated

Thursday, 12 December 2024

An extended treatment plant able to process an extra 20 million litres of water a day has led to a dramatic downgrade in water risk in Wellington this summer with the chance of extreme measures now under 1%.

The upgraded plant beside the reservoir lakes at Te Mārua, Upper Hutt came in ahead of time, Wellington Water Committee deputy chairperson and Greater Wellington Regional councillor Ros Connelly said.

The upgrade was funded by the regional council, which put the cost of the total project at $89 million in its latest long-term plan.

Wellington Water said the project would cost between $90m and $100m. The programme was about 80% completed and final numbers would be provided once it was finished.

“We are unlikely to experience the most-extreme water restrictions that were a real risk last [summer],” Connelly said.

Excessive leaks from ageing pipes mixed with a dry summer of 2023-24 led to long lines as people tried to buy a small stock of rainwater tanks. The region was put under level 2 water restrictions meaning unattended watering was banned.

But there had been a real risk of level 3 restrictions which would have banned all outdoor water use and people being asked to reduce indoor use. There was also a risk of a regional state of emergency being declared. Wellington is currently under level 1 restrictions meaning people can use sprinklers only every second day between 6am and 8am then 7pm to 9pm.

But Connelly said the upgraded facility, mixed with Niwa’s summer prediction and some leak repairs, meant it was unlikely the region would go above level 2 restrictions. The facility meant another 20m litres could be treated per day, increasing capacity by about 10%.

Wellington Water modelling had a 100% chance of level 2 restrictions last summer but that was 5% for this summer. Level 2 chances dropped from 70% last summer to 1% while level 4 dropped from 33% to less than 1%.

More capacity would be added in future years, she said.

Wellington Water Board chairperson Nick Leggett warned there were factors, such as a plant failure or no rain, that could still mean harsher restrictions.

The work had been fast-tracked due to the pressing need that was highlighted last summer, he said.

“Greater Wellington took action when it was needed, and this has enabled the team to work tirelessly to deliver this vital project ahead of schedule,” Leggett said.

“With the additional supply from Te Mārua now online, the risk of tighter water restrictions has significantly dropped – for this year. This gives the region some short-term cover with its drinking supply, but it is not even a medium-term safety blanket.

“We must crank up renewals of pipes to reduce water loss, meter and charge for our water and plan and build more water storage.”