Aucklanders will be paying more for water from July, with water and wastewater service prices increase by 9.5 percent.

Watercare chief executive Dave Chambers said the rise was in line with the price path approved by the board of directors in December 2020 and included in Auckland Council's Long-Term Plan.

"Since the board approved the price path in 2020, we've faced significant challenges, including very high rates of inflation and extreme weather events ranging from drought to the recent floods."

Households with average use would pay about $2.20 more a week, he said.

"We encourage our customers to get in touch with us if they're struggling to pay their bills. We can work out flexible payment plans or refer them to the Water Utility Consumer Assistance Trust which we fund to support customers suffering genuine hardship."

Infrastructure growth charges will rise by 8 percent from 1 July 2023, the council-owned company said.

The price for 1000 litres of water will go from $1.825 to $1.998, while 1000 litres of wastewater will go from $3.174 to $3.476.

The fixed wastewater charge will go from $264 a year to $289.

Chambers said the company had focused on reducing costs and without that Aucklanders would be looking at a 10.7 percent rise.

"One of the ways we've made savings is by reducing our overall head count through attrition. We've gone from having 1255 full-time equivalent staff in June 2022, to 1198 in January 2023."

Watercare's board considered whether it could defer spending given the cost of living crisis but it couldn't be put off any longer, Chambers told Morning Report.

The 94-year-old Huia water treatment plant in the Waitākeres, for example, was not able to be used during heavy rain and would cost $800m to replace.

Watercare had borrowed as much as it could within the constraints on debt levels as a council-owned organisation. Under either government's Three Waters policy or National's alternative it could borrow more which would result in lower prices than otherwise planned, he said.

Inflation had put up cost of imported chemicals to treat water and wastewater by the "hundreds of percents".

It had put in efficiency savings of 3-4 percent off costs, irrespective of inflation, every year for the next five or six years.

Watercare has estimated the cost of the recovery from Cyclone Gabrielle and Auckland Anniversary flooding at more than $250 million.