Paul Eagle and Tory Whanau are neck and neck to become Wellington's next mayor, while incumbent Andy Foster is lagging behind, a Q+A Kantar Public Poll suggests.

Kantar Public polled 500 Wellingtonians about their voting intentions and asked them to rank as many or as few candidates they wanted in order of preference. Wellington City Council uses the single transferrable vote (STV) system to elect its mayor, meaning people's preferential votes are reallocated as required until one person is left.

Thirty-five per cent said they didn't know who they would vote for, 7% refused to say, and 5% didn't plan to vote.

Excluding these three groups, of those who said they were likely to vote, their first preferences for mayor are:

Once various candidate preferences are accounted for under STV, it's a virtual toss-up:

Kantar Public stressed the results weren't projecting an Eagle victory because it is statistically too close to call and the number of undecided voters is high.

Foster had previously told Newstalk ZB he saw things as a "two-horse race" between himself and Eagle. When Q+A asked why he wasn't further ahead, the Wellington mayor said of his rivals Whanau and Eagle: "There's not a lot between the three of us."

He said while things had been tough in the past three years, he had gotten things moving that previous councils had not. Foster said he needed another three years to finish the job he started.

Eagle, Labour's Rongotai MP, said he wasn't taking the poll result for granted because there was still a long way to go.

"Wellingtonians are intelligent people, they know politics well. They are looking closely," the former Wellington City councillor and deputy mayor said.

But just two years ago, Eagle had ruled out running for mayor in 2022. So, could voters trust him to keep his word?

"Wellingtonians came to me - many of them - and said we want you to stand," Eagle said, adding he brings a vision and plan for the capital.

Former Green party chief of staff Whanau said she was "really excited" about the poll results because she was a relative newcomer. She said it showed people wanted change.

Kantar Public also asked Wellingtonians what issues they cared most about.

Fifty-seven per cent said they want the mayor to prioritise the city's run-down pipes. The next most important issues for voters are climate adaptation, road improvements and maintenance, reducing rates where possible, and investing more in public transport.

But who was responsible for the state of the city's water infrastructure?

Foster said previous councils had failed to allocate the necessary investment. He said, when he was first elected, the "pipes started failing almost immediately".

He said his council had increased the 10-year budget for pipes from $1.85 billion to $2.7 billion.

"Every time we were ever asked for resources by a water company… we always said yes."

Foster didn't support the Government's Three Waters reforms. But, if it went ahead, he said he would give the new water entities all the asset management data they needed.

In the possibility the reforms didn't go ahead, the council would be "stepping up" investment regardless.

Eagle, who was on the city council between 2010 and 2017, said he would prioritise the issue as mayor.

He said the council had invested in the infrastructure during his time, but that he hadn't been a sitting councillor for five years now.

Eagle promised to work with central government to roll out improvements as part of its Three Waters programme.

Whanau supported the Three Waters reforms because she believed it would be too expensive for ratepayers to try and play catch up after years of underinvestment in water infrastructure.

But what if the Government's reforms don't go ahead? Whanau said ratepayers could be facing a "hefty increase" if that happened - although she couldn't say how much - because an alternative needed to be found.

Whanau said her plan relied on the Three Waters reforms going through.

Read the results and methodology here.

Between August 31 and September 8, 2022, 500 eligible Wellington City Council voters were polled online, using online panels. The maximum sampling error is approximately ±4.4 percentage points at the 95% confidence level. For candidate support, percentages have been rounded up or down to whole numbers. Undecided voters, non-voters and those who refused to answer are excluded from the data on candidate support. The data have been weighted to align with Stats NZ population counts for age, gender, ethnic identification and education in Wellington City Council. The online sample is collected using an online panel.