Erica Williams, 22, thinks she would be dead if authorities had not had the power to keep her in treatment last year.

Key points: Psychiatric patients are being discharged from hospital with nowhere else to go due to bed shortages, royal commission told

Psychiatric patients are being discharged from hospital with nowhere else to go due to bed shortages, royal commission told In some parts of Melbourne the number of acute mental health beds available is half the OECD average

In some parts of Melbourne the number of acute mental health beds available is half the OECD average Victoria's chief psychiatrist said there was pressure to move patients through the system before they're ready to be discharged

"If I didn't have compulsory treatment I think I would have committed suicide," Ms Williams told the Royal Commission into Victoria's Mental Health System on Monday.

"I absconded from [treatment facility] Orygen four times.

"Each time I was leaving with the intent to commit suicide."

Ms Williams testified that fearing for her safety, her doctor would sometimes place her in compulsory treatment as a tactic to prevent her being discharged.

"Even if I felt like I could be a voluntary patient in a hospital, sometimes my psychiatrist would put me on a compulsory treatment order, so that we could avoid premature discharge," she said.

"It often gets a bad rep, which I understand because there's the possibility of violations of basic human rights, but at the same time, if I didn't have it, I think I would have committed suicide."

Her evidence came as two psychiatric administrators and Victoria's chief psychiatrist testified that inadequate beds meant facilities were forced to discharge patients prematurely, even knowing they had nowhere else to go.

"There is no doubt that we are sometimes forced into discharging into unstable accommodation or even homelessness," NorthWestern Mental Health director Ruth Vine said.

She described the situation as "a terrible tragedy".

Professor Vine said in some parts of outer-metropolitan Melbourne there were just 11 acute mental health beds per 100,000 people — half the national and OECD average of 22 beds per 100,000 people.

"The capacity has remained the same, while the population has exploded," she said, referring to the number of people each facility had to treat.

Head of the Alfred Hospital's psychiatric unit, Simon Stafrace, told the commission that Victoria averaged 19 beds per 100,000 people.

"I see a lot of people come in [who are] in need of acute beds and there aren't enough," Dr Stafrace said.

Hospital stays now one third shorter

Victoria's chief psychiatrist, Neil Coventry, said patient data showed that people who did get beds were staying an average of 9.7 days.

"A decade ago, our length of stay was around 15 days," Dr Coventry said.

"Which means the time that someone's actually in an inpatient acute unit to get those sort of interventions is really diminished dramatically."

Dr Coventry said the declining time in care was due to the "pressure" to "move people through before perhaps they're really ready to be able to discharged".

Victoria's Government has committed to implementing the recommendations of the four-week inquiry, which has heard of people being turned away because they were not deemed sick enough, and yawning gaps between adolescent and adult care.

"We know it's going to be costly," Mental Health Minister Martin Foley said last week.

"Without more inpatient capacity, I don't know how we will get beyond our current dysfunctional state," Dr Coventry said.

The royal commission is due to deliver an interim report by November, with a final report due in October 2020.