Kerikeri households and businesses could see hefty rates rises in three to five years' time from an expanded sewerage scheme.
The exact amount, however, won't be known until March next year.
The Far North District Council says it has no choice but to upgrade the town's ageing sewage system. Hundreds of properties in the centre of town still rely on septic tanks and the 25-year-old sewage plant can no longer treat wastewater to the required standards. The plant's consent runs out in 2015.
Another reason for urgency is a multi-million-dollar Health Ministry subsidy which could be lost if the council delays any longer.
In a major consultation exercise last year, called Let's Talk Crap, Kerikeri residents gave the council the green light to hook up any CBD properties still on septic tanks and expand the scheme to Riverview.
A suburb on the northern side of Kerikeri River, Riverview was felt to be important because of its proximity to Kerikeri Inlet and soils unsuited to septic tanks.
A new plan released this month, however, omits Riverview and instead focuses on the 340 properties in central Kerikeri still using on-site treatment such as septic tanks. And instead of building a new treatment plant in the Waitangi Forest the council has opted to expand the current plant on Shepherd Rd.
The changes slash the total cost from a previous estimate of $30m to a more affordable $14.2m.
In a statement released this week, Mayor John Carter said councillors had reviewed a number of projects inherited from the previous council in light of the Auditor-General's report into the cost blowout at Kaipara District Council's Mangawhai sewerage scheme and a slowdown in Kerikeri's growth.
Councillors considered options ranging from the $42m Bay of Islands Sewerage Scheme proposed more than 15 years ago to a $2.4 million "quick fix" which would improve the quality of treated wastewater but not allow any more households to be connected.
Mr Carter said the council had no option but to upgrade the treatment plant which had been operating at full capacity for the past seven years. The council could be hit with costly legal action if treated effluent kept breaching resource consent standards.
The expanded plant would be designed so Riverview or other areas could be connected in future.
Households and businesses connected to the scheme would face significant rate increases when the scheme was built in 3-5 years' time. The exact dollar value of those increases would be known once the scheme's design was finalised and the council's Draft Long Term Plan was released in March.
Council staff have already started talking to people who live near the plant in Shepherd Rd or along the route of the pipeline carrying treated effluent to the discharge point in Waitangi Forest. Everyone else will be able to comment next year.