The lid needs to be lifted from time to time to ease the pressure or it will eventually boil over, he said.
While rates capping can provide rates relief to the community, it won't provide the level of service and infrastructure growth communities need, Broughton said.
This is made up of 14.9% this year, 14.2% in 2025/26, and then 13.3% forecast for 2026/27.
Broughton said those figures are not manageable long term but the council was having to play catch up from when rate increases were perhaps too low.
During Covid, Selwyn had a 1.6% increase, he said.
Homeowners across New Zealand faced some of the biggest rates rises of their lifetime last year as councils were hit by rising interest rates, higher insurance premiums, and increasing infrastructure costs.
Local Government Minister Simon Watts recently told RNZ the Government plans to introduce a bill in June to refocus councils on "doing the basics, brilliantly".
The government hasn't ruled out rates capping, which would limit the amount by which a council can increase its annual rates.
As the Local Government NZ president, Broughton has been a vocal critic of rates capping.
Speaking as the Selwyn mayor, he said the measure doesn't fit for his growing district, which includes Rolleston, Prebbleton and Lincoln.
The Government has been calling on councils to focus on core functions, which Broughton believes Selwyn is doing.
Of Selwyn’s capital spend, 86% was on roading, drinking water, and wastewater.
“That doesn’t include our rubbish, recycling, community centres or other things that our community wants.
“We are doing the basics well and planning for our future.”
As a growth region, Selwyn faces the cost of providing infrastructure ahead of time, he said.
“We would like to see lower rate increases for our community and to be able to do that we need new funding tools from the government.”
Local Government NZ has suggested several options to the Government, including councils receiving the GST from new builds - which Broughton says would have benefits for Selwyn.
Population growth has increased the number of ratepayers in Selwyn, but it has also increased the costs to cater for a larger population.
The district is also more than just the new growth areas around Rolleston, Lincoln, Prebbleton and West Melton, he said.
“Many of our towns are over 100 years old so there is infrastructure right across the district that will always need maintenance and renewals.
“What we have seen in big cities like Wellington is that if you don’t have good maintenance plans – and funded plans- the problems come to the surface pretty quickly.
“In Selwyn, we want to be proactive and don’t leave our children, grandchildren and great-grandchildren with huge deficits because we weren’t willing to invest in the infrastructure we need now.”
Former Selwyn councillor Mark Alexander, who is now chairperson of the Rolleston Residents' Association, said in his personal opinion he was against capping rates to an arbitrary number or percentage increase.
"[It's] stupid and those who suggest it are at best naive and at worst malicious.
“Every council makes an effort to minimise any increase in their rates but council face ongoing increases in costs including unfunded mandates from central government.
“To artificially cap any rates increase will almost certainly mean that councils have to reduce the amount of maintenance and renewals of their infrastructure, which will mean bigger rate increases in the future to catch up with the deferred work.”
He pointed to leaky water pipes in Wellington and Auckland caused by decades of deferred maintenance, which kept rates artificially low.
“Deferring maintenance on your car or home doesn't make the need for the work go away, it just means it isn't done and will need more work, at more cost in the future.
By Jonathan Leask, Local Democracy Reporter
■ LDR is local body journalism co-funded by RNZ and NZ On Air.
