A vital part of the water treatment system unexpectedly failed and put the pool out of action, leaving school and swimming carnivals in limbo.

With the competition season still in full swing, those swimmers will now have to train for upcoming events in 25-metre indoor pools rather than the 50-metre pool.

Warrnambool Swimming Club coach Jayson Lamb said he hoped the incident helped push the need for a new 50-metre pool up the priority ladder.

The aging facility has been the subject of debate amongst councillors, with Cr Ben Blain campaigning for a major upgrade.

"I think the closure of the pool show how much we are in need of a new facility," he said.

Cr Max Taylor has said the 60-year-old outdoor pool needed money spent on it.

In December, the council set aside $200,000 for a feasibility study into whether to rebuild AquaZone's at the current site, move or combine it at a new multi-purpose sporting facility.

Cr Blain said work on the study would begin soon, and it was a top priority for the council. "We need to get moving," he said.

The outdoor pool - which was expected to stay open for an extended season - was closed on Wednesday when an injection valve that is part of the water treatment system failed.

It cannot be repaired without the pool being emptied.

City council chief executive officer Peter Schneider said it was very disappointing given it had been a great summer and there were plans to extend the outdoor pool season to March 27.

"This is a relatively new component, installed in 2019, that has failed between quarterly inspections," Mr Schneider said

"We were losing about 1200 litres of water an hour which we couldn't sustain any longer.

"We had hoped temporary measures might allow us a few more days to accommodate some swimming carnivals but unfortunately they have not been effective.

"To carry out a proper repair means we need to empty the pool and it would not be feasible to refill the pool for another week or two of outdoor swimming this season."

The pool closure is a blow to swimmers in the south-west who have been battling to continue training during COVID-19 restrictions and pool closures.

AquaZone has also struggled to keep the outdoor pool open as it battles staff illness during the Omicron wave and a shortage of trained lifeguards.

Mr Lamb said the long course season didn't finish until April with a number of swimming events coming up.

"So access to the 50-metre pool would be hugely beneficial, especially to those who are close to a national time," he said.

"At the end of the day it is what it is, as disappointing as it is you've just got to deal with it and move on."

Mr Lamb said it was a very old facility and it was "well overdue" for an upgrade.

The council has apologised to user groups and said the failure of the component could not have been foreseen.

It has yet to be determined how much it will cost to repair the pool, but they would be done in time for the 2022-23 season.

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