New housing developments in Auckland's Warkworth will be unable to be built or lived in until a new wastewater treatment facility is built.

The wastewater treatment plant on the Mahurangi River, which services the area, is nearing capacity.

While Auckland Council is still issuing resource consents to developers, no wastewater connections can be made to properties south of the river until the new facility in Snells Beach is completed.

The facility was due to be finished by mid-to-late 2025, but for developments north of the river, it could be years before homes could be lived in as a new Northwest growth pipeline needed to be made and this was still in planning stages, WaterCare said.

According to it, more than 20,000 people were expected to be living in the area in the next few decades, which Auckland Council has identified as a possible "satellite city".

The Warkworth community was growing "significantly", WaterCare chief strategy and planning officer Priyan Perera said, and a "huge programme of work" was under way to overhaul the area's wastewater service.

"Construction is progressing well at the new treatment plant, and we're moving into the installation phase of the project."

The Northwest pipeline

One Mahurangi Business Association manager Murray Chapman said the wastewater line was still in the planning phase.

The association worried the construction route would cause significant disruption to businesses in the main street.

"They haven't publicly announced the route yet, but we believe they want to trench the main street which will see our businesses collapse due to the impact caused by ongoing construction."

Disruption while the pipeline was built could take over a year, Chapman said.

"We've had Covid-19, the motorway bypass and the economic downturn to deal with, and this would be the final nail in the coffin for many businesses," Chapman said.

Perera confirmed a pipeline through the town was an option WaterCare had been considering and a "balance" would need to be found between the short-term impact of the works and the long-term development of the infrastructure.

WaterCare chief strategy and planning officer Priyan Perera. Photo: LDR / Stephen Forbes

But Chapman said WaterCare should reconsider its options if it wanted to keep the town centre "vibrant".

"Developers are ready to go and have spent lots of money on land up here. They want things to happen and they want a vibrant town centre to help sell sections and they won't have that if the pipeline route goes through the main street.

"This has to be done, no one is disputing that, but there are other options and routes that WaterCare could take."

Developers had been "supportive" of the pipeline plans, Perera said.

"We understand locals have some concerns and we are willing to listen and meet with people. We intend to work with communities while focusing on balance."

Any developers that wanted to apply for resource consent in Warkworth should get in touch with WaterCare first, Auckland Council resource consents manager Ian Dobson said.

"The council still has the ability to approve applications for development but with a condition that development cannot commence until there is an approved connection to WaterCare wastewater infrastructure."

Dobson said he was not aware of any developers choosing not to build in Warkworth due to the wastewater upgrades.