A 28 per cent increase in supply across Sydney's rental market has failed to push down prices, with less than 1 per cent of properties in Sydney's market considered "affordable", a survey of rental properties has revealed.

The Anglicare Rental Affordability Snapshot surveys all the private rentals available in Australia over a weekend in March.

This year Sydney ranked the worst of all major cities with only 57 out of the more than 18,000 private rental properties canvassed across Sydney and Illawarra — or less than 1 per cent — deemed affordable for people on income support payments.

The national rate was 6 per cent.

None of the private rental properties in the Sydney area were suitable for single people on Newstart or Youth Allowance.

"There were only half a dozen available out of that 18,000 for families that were a couple with two children on Newstart," Anglicare's head of research and advocacy Susan King said.

"We found that for single parents on a parenting payment there was nothing available, for a single parent on Newstart with one child it was the same."

Rental properties are considered "affordable" if they cost up to 30 per cent of a person's income.

Western Sydney homelessness growing

Western Sydney mother of three Siale Hausia said the stress of paying rent left her constantly on edge.

In 2016 she was a stay-at-home mother when her then-husband lost his job.

Without a stable income, their $550-a-week rent became too much.

The financial pressure took a toll on their marriage, and Ms Hausia and her children ended up staying with a cousin in her one bedroom home.

Eventually, they ended up in a refuge.

"I didn't have any choice, I had to go to community centres to ask for help," Ms Hausia said.

"The only option I had was a refuge because there's no way they give a single mother of three kids living on Centrelink a place, there's no way."

Siale Hausia ended up in a refuge with her three kids Vaohoi, 8 (front) Ta'a, 11 (left) and Lotu, 13 (back). ( ABC News: Kathleen Calderwood )

The latest census data on homelessness shows a startling increase in Sydney's west.

Between 2011 and 2016 the number of homeless people in the Parramatta area more than doubled; the south-western suburbs went from 2,100 to 3,071 homeless people and homelessness in the inner-south-western suburbs grew by more than 50 per cent.

Ms Hausia said it took five or six months to find somewhere suitable to live. She now works as a disability support worker.

But she still worries about not being able to pay the rent.

"You're living on the edge because you don't know what's going to happen next," she said.

"They might cut your Centrelink, and then you can't afford the rent and you have to leave, or they put up the rent and you can't afford it.

"I never say no to work, I work hard to not go back to refuge and not go back to being homeless. I don't want my kids to go through that ever again."

More public housing desperately needed: Anglicare

Ms King said an increase in supply has not helped low income earners, and there needs to be an increase in public housing.

"Even though there are 28 per cent more listings available it hasn't translated to increased affordability," she said.

"There's a huge crisis in terms of public housing and the lack of public housing in NSW — there's very long waiting lists, you've got a lot of people queueing up.

"Until those issues are resolved I think the private rental market is still going to be very, very tight for most people."

Government defends housing policies

The NSW Government has defended its public housing policies and pointed to its long-term plans to increase the number of affordable rental homes.

Finding an affordable home is hard work in Sydney ( ABC News: Giulio Saggin )

A statement from the Department of Family and Community Services said the Government was undertaking the biggest social housing building program in the country to deliver 23,000 social and 500 affordable homes by 2026.

"The program includes five major sites for development in Sydney and Greater Sydney including the Ivanhoe Estate," the statement said.

"The sale of ageing social housing in Millers Point is financing the construction of social housing across the wider Sydney area, including Bankstown, Canterbury, Liverpool and Fairfield areas and the Sutherland and Wollongong areas.

"As of March 2018, a total of 872 units have been completed and 310 units are currently under construction as a result of the Millers Point sales.

"In total, more than 1,500 new homes will be provided for some of the most vulnerable people in New South Wales as a result of the Millers Point sale, including many on the social housing waiting list."

However, Opposition housing spokeswoman Tania Mihailuk said the data showed the Government's housing strategy was failing.

"The latest data cast doubt on the Premier's assertion that adding new housing supply improves affordability," she said.

"If you don't actually mandate affordable housing targets when you are increasing supply, you just end up with more unaffordable properties."