The prison has 29 beds for women, but with as many as 45 female prisoners at a time this year, it has had to give them beds in the health unit and the "management unit", officials have told ACT parliament's estimates hearings.

Corrective Services executive director Jon Peach said the directorate was looking at whether it could "repurpose" existing beds at the prison, while ensuring women were still kept separate. If that was possible, it could create space for 57 female beds.

The directorate was also considering reopening Symonston, which had been decommissioned. That would depend on how much work was needed to bring it up to scratch.

Liberal Giulia Jones, who questioned Mr Peach and the other officials, said it was a "shambles".

"If things continue to rise at this rate what are we going to do with all these women?" she said. "They are maxed out having women in both the health centre and the management unit. There aren't actually any spare beds on the nights when we have 45 women. What's going to happen when they have 50?"

A justice spokesperson said later that female numbers had almost doubled in six months, but over the past few weeks numbers had been falling again. There was no need to move anyone at the moment and no decision had been made to recommission Symonston, which had been empty since February last year.

"Should the government consider there to be a need to recommission Symonston, appropriate consultation will occur with the community and an announcement would be made ahead of doing so," the spokesperson said.

"The Symonston facility remains as one option available should the need ever arise but ACT Corrective Services will also consider alternatives."

Mrs Jones said she had visited a NSW women's prison recently and been impressed with the level of care.

"I do feel that women in the Alexander Maconochie Centre are treated like a small afterthought after everything is organised for the men," she said.

She questioned how many hours women would have to spend locked up in the management and health units, compared with the cottages where they can move around and cook for themselves.

And she questioned officials about the number of rooms in the management unit, suggesting there might be only seven rooms housing the 14 women.

"It's just not good enough that there is no alternative plan. This is not a new problem," she said.

Mrs Jones told Mr Peach that last time she visited the prison the beds in the health unit were "a big box with a sort of a foam kind of a mattress on top, which were used for examinations".

"Is there actual proper bed accommodation and do they have bathrooms or what kind of accommodation is that in the health unit?" she asked.

But Mr Peach said she was referring to the crisis support unit, rather than the health unit. The health unit had two larger rooms, with four beds.

Gordon Ramsay, standing in for Corrections Minister Shane Rattenbury, said the increase in the number of female prisoners, especially on remand, had not been anticipated.

"In the last two years the numbers have increased rapidly," he said. "... While last year's successful AMC accommodation expansion project catered for the existing and the forecast increase in the number of male detainees, forecasts did not predict the extent or the speed of the rise in female detainees."

Women were always housed separately.

Symonston was used for more than 20 years for periodic detention, and to ease alleviate pressure on the overcrowded Belconnen Remand Centre. The Human Rights Commission criticised both remand centres in 2007 for allowing little time out of cells and for excessive lockdowns. At Symonston, prisoners could not access the rehabilitation and other programs run at the main prison.

But the justice spokeswoman said Symonston had CCTV and a secure perimeter fence. It had 30 beds. When the government reopened Symonston temporarily to cope with an overflow of male prisoners in June 2015, they had had access to all facilities and visits available to prisoners at the main prison.

The ACT's prison has been plagued by overcrowding problems since soon after it opened in 2008. Last year's expansion means it now has room for 539 prisoners, up from 370.

The average number of detainees rose from 294 in 2013 to 336 in 2014, and to 373 at the end of 2015.