A lobby group pushing to save Hamilton's historic Municipal Pools are vowing to fight any moves to permanently shut the complex.

City councillors will meet next week to vote on the pool's future, with a staff report recommending the pool remain closed and an alternative use for the Victoria St site be explored.

The recommendations come on the back of an investigation by Opus International Consultants which highlights significant structural issues with the complex.

Councillors closed the century-old pools complex in May while a major leak was investigated.

Testing revealed the pool leaks up to 37,325 litres a day.

Councillors will be presented with a range of options for the site, with staff estimating a major upgrade of the facility could cost more than $4 million with operational costs estimated at about $280,000 a year.

Sealing the existing pool is not considered an option because of the "inadequate strength" of the main pool walls.

But Community-based pools support group Sink or Swim are challenging the council's costings and plan to address councillors next week.

Group spokeswoman Katherine Luketina said the council report was unsurprising but questioned its costings.

"We have had a very experienced, qualified building engineer do costings and to bring the complex back up to standard would $1.5m. That cost would be spread over several years and would give you a fully compliant pool without any bells and whistles."

Ms Luketina predicted a "ground swell" of opposition to any moves to permanently close the complex, noting 2500 people had signed a petition advocating the pool remain open.

"The pool was leaking for a long time before the council decided to become concerned and close it. There's no reason why they can't operate the complex while it looks for solutions. It's council inaction that has caused the current state of the pool."

There have been no significant upgrades to the pool, plant, or pipe work in recent time. The council report acknowledges the complex has deteriorated in the past 10 years while "the maintenance budget spent during that time has been minimal".

"This has resulted in the pool not complying with the current swimming pool design standards and water quality standards cannot be maintained."

The report also notes the Municipal Pool's patronage figures for 2011/12 (13,557) were low compared with Waterworld and Gallagher Aquatic Centre's patronage figures of 639,000. Ms Luketina said the council had done "zero" advertising to promote the complex, with previous patronage numbers as high as 70,000.

- © Fairfax NZ News