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Regional | Water

Tāmaki Makaurau water storage boosted by 45-million litre reservoir

The building is the equivalent of 18 Olympic-sized swimming pools, takes five days to fill and cost $60 million.

Aotearoa’s largest city has made a significant step towards securing its water future with the inauguration of a new 45-million-litre reservoir at the Redoubt Road Reservoir Complex in Tōtara Park.

This addition, the equivalent of the volume of 18 Olympic-sized swimming pools, is a part of a broader $60 million project aimed at bolstering the city’s treated water storage capacity.

The Redoubt Road complex, already the city’s largest reservoir site, plays a pivotal role in Auckland’s water supply system. It receives water from the Ardmore and Waikato treatment plants, with 80% of the city’s treated water supply passing through it daily.

The new reservoir elevates the site’s total storage capacity to 165 million litres, thereby increasing Auckland’s overall treated water storage capacity to more than 700 million litres.

Watercare chief infrastructure officer Steve Webster highlighted the significance of the new reservoir in supporting Auckland’s anticipated population growth. “Over the next two decades, Auckland’s population is expected to grow by 29%, taking the city’s current population of 1.7 million to more than two million people,” he said.

Coping with ‘unplanned events’

Webster said the addition of the third reservoir not only provided greater operational flexibility but also ensured enhanced security over Auckland’s water supply.

“The reservoir provides us with an increased volume of water storage that we can draw on to maintain water supply for our customers in the event of an unplanned event such as a major power outage or natural disaster,” he said.

The construction of this vital infrastructure spanned more than 30 months and was started in late 2021. The project saw significant earthworks and the use of over 8,000m³ of concrete, including extensive overnight pours to shape the reservoir’s floor and roof.

Martin Hughes, the project manager at Watercare, emphasised the thoroughness of the pre-service checks. “Water tightness testing is a standard procedure used globally to confirm water retaining structures are fit for purpose before they are brought into service,” he said.

“It’s one of the last tests we do before commissioning, as it requires us to fill the reservoir over four to five days until it reaches its maximum operating level.

The complex has potential space for up to eight reservoirs. Final touches include new site roads, fencing, and landscaping.