File photo. Photo: 123RF
Almost $1.3 billion needs to be spent on Lower Hutt's ailing water infrastructure over the next 30 years.
Hutt City Council says a new study from regional water service provider Wellington Water confirms the massive scale of the investment needed.
Drinking water storage reservoirs need to be expanded, as do wastewater pump stations, and underground waste water and storm water infrastructure needs to be upgraded.
The council has doubled the amount of capital expenditure in its most recent Long Term Plan, but still only has about 18 percent of the renewal budgeted for.
The population of the area is expected to grow by a quarter in three decades.
On average $35 million in additional funding will be needed per year for the next 30 years, to meet growth demands and bring networks to target levels of service.
Stormwater improvements make up 64 percent ($810m) of the estimated investment to provide these essential services for the expected population growth.
Wellington Water chief executive Colin Crampton noted the council's current level of water investment was considered good in terms of halting the backlog of renewals, but council was still behind.
"A peer review by the Water Industry Commission for Scotland suggested the level of capital investment was on the light side based on comparisons with other cities," he said.