The bill for fixing Whanganui's strained wastewater system to stop sewage seeping into the river is set to cost ratepayers an extra $50 million over the next 30 years.
At a meeting on Thursday Whanganui District councillors were told stormwater was regularly overwhelming the sewerage network during heavy rain.
The council's Three Waters manager, Kritzo Venter, said these overflows were in breach of Horizons Regional Council's Regional Plan.
Whanganui District Council was legally required to mitigate any health risks under public health legislation.
"Any areas on public or private property where overflows occur are decontaminated by council contractors."
Some stopgap measures had been made in places to "minimise and isolate any health risk to high-use areas or private properties", Venter said.
The council is spending about $200,000 a year to investigate leaks, identify underground faults and do running repairs and targeted renewals.
As part of the council's Infrastructure Strategy 2021-2051, roughly $50m had been budgeted to upgrade the stormwater system's public network, including pipes, pump stations and new wet weather storage facilities.
Council chief executive David Langford said it was important the community was aware of the problem, what was required to fix it and how the work would be funded.
"We want to be open and transparent with our community and be clear about what they can expect to see going into the future. Currently the network is not performing as it should in wet weather and the community should rightly expect us to come up with a proper and permanent fix."
The council also needed to consider "a more robust compliance framework" to track down property owners with non-compliant stormwater downpipes and yard sumps, he said.
Mayor Andrew Tripe said news of this looming cost will be a shock to ratepayers already struggling with the cost of living.
"Even though there is uncertainty around how our water services may be delivered in future, with Three Waters reform legislation currently going through Parliament, it is important we do the planning we can, while we can.
"We need to do the right thing by making sure wastewater isn't getting into the environment," he said.
"We are also working with the proposed new Manawatū-Whanganui water services entity to make sure our asset management plans are aligned."
RNZ
