Growth in Auckland's northwest is more likely to be catered for by the North Shore sewage treatment plant than a new facility as previously mooted.
A draft strategy looking at future wastewater service needs says provision must be made for a mate to the regional wastewater treatment plant
at Mangere.
In the late 1990s, Watercare raised the prospect of building a satellite plant near Taupaki to increase treatment for West Auckland, including Kumeu, Huapai, Waimauku and Riverhead.
But Watercare chief engineer Jim Hodges told Auckland Regional Council members that the logical next regional plant is the North Shore City Council's Rosedale plant in Albany.
It has been expanded over the past decade to provide for North Shore's population of 200,000 and for growth for 50 years. A huge outfall to the Rangitoto Channel now under construction will give 100 years' future-proofing for that plant.
Mr Hodges said Rosedale needed to be identified as a future regional facility and given planning protection against neighbouring development.
Rosedale had far more advantages than four other alternatives investigated to provide for an extra 500,000 people.
By contrast, a northwest plant site was 55m to 60m above sea level, which would mean higher energy costs in pumping wastewater to and from sites.
The discharge would affect the environment and community not currently affected and would cost $173 million more than using Rosedale.
ARC councillor Christine Rose said the evidence against use of the Taupaki site would come as a relief to northwest residents facing a sizeable plant on their doorstep and the possibility of an outfall to the Tasman Sea.
"Watercare had to look at a regional plant at Taupaki because it bought the land some time ago. I hope this strategy rules it out once and for all."
Rodney District Council member Suzanne Weld said the Kumeu, Huapai and Riverhead community wanted its own plant separate from Watercare.
The council was applying for resource consents for a plant with land disposal of treated effluent and to work with owners of land that could be freed up for housing to help fund the first stage of the plant.
