The pool - which the government says is at the end of its usable life - was due to close in June.

An amended motion, moved by the Canberra Liberals, to keep the hydrotherapy pool open until a viable alternative was delivered in Canberra's south was passed in the ACT Legislative Assembly on Wednesday.

Arthritis ACT chief executive officer Rebecca Davey had raised concerns the group would have to turn clients away due to capacity issues when the pool closed, while some users would not be able to travel to the north.

Health Minister Meegan Fitzharris had previously said classes could be managed through the pool at the University of Canberra Hospital and other pools in the territory.

About 15 members of Arthritis ACT were present in the public gallery to watch the motion pass.

In agreeing not to close the pool until comparable services were available, Ms Fitzharris said Canberra Hospital's pool - built in the 1960s - was ageing and expensive to maintain.

She said consultancy firm Nous Group met with ACT Arthritis on Wednesday morning to consider alternative hydrotherapy sites accessible for people on the south side.

Ms Fitzharris said Arthritis ACT had reported a 40 per cent increase in demand for hydrotherapy services in the past three months and Nous Group would investigate that growth and determine how to meet it.

She said the group would present a report to her by June outlining future options.

The pledge comes after Ms Fitzharris promised in estimates last year that the new Stromlo pool would have a hydrotherapy pool in it.

But it has since emerged the pool is not warm enough to be classified as a hydrotherapy pool and is not able to be used for therapeutic reasons.

Opposition health spokeswoman Vicki Dunne welcomed Ms Fitzharris' pledge to keep the pool open.

"This is great news for every hydrotherapy pool user in Canberra's south," she said.

"I still do not understand why the Health Minister wanted to unfairly discriminate against health patients in Canberra's south.

"It was wrong for Ms Fitzharris to put people in Canberra's south through this stressful ordeal.

"While it should never have come to this, I am pleased Ms Fitzharris has seen the error in her ways and will keep the pool open until a new hydrotherapy pool with the appropriate specifications is made available in Canberra's south."

Mrs Dunne said the Liberals would "keep a very close eye" on the situation to ensure there is a hydrotherapy pool that is heated to the optimum temperature of 34 to 36 degrees in Canberra's south.

"If Ms Fitzharris and the Labor-Greens government are true to their word, then this is great news for people in Canberra's south," Mrs Dunne said.