With almost 40 per cent of her weekly income going towards the $580 rent on her Green Valley home, the 39-year-old single parent has become skilled at juggling bills and spotting the supermarket bargains to make ends meet.

"I try to do my best," she said.

"The rent, the gas, the electricity, the phone, the food, medical expenses, school and clothes - everything adds up. It's hard. It's really difficult. Some days I do feel like I'm living on the edge."

New data on rental affordability from Anglicare shows Ms Suarez is not alone.

Researchers from the social welfare group examined 14,500 properties available for rent in greater Sydney and the Illawarra, finding only a handful were affordable and appropriate for people on low incomes of less than $36,000.

Just 30 properties (or 0.2 per cent) were suitable and affordable for households on social security benefits - less than half the number compared with this time last year, when the figure was 76 or 0.5 per cent.

The situation also worsened for households on the minimum wage. The report found 2228 (or 15.4 per cent) were suitable and affordable for this group, compared with 2618 (or 17.7 per cent) a year ago.

'Affordability' was defined as spending less than 30 per cent of household income on rent, a widely-used measure of rental stress.

Sue King, Anglicare's Sydney advocacy and research manager, described the Rental Affordability Snapshot results as the worst in the seven years the organisation has been analysing rental affordability.

"I was pretty gobsmacked," she said. "It's the bleakest story we have ever told in terms of rental affordability for people on low incomes and Sydney is the worst in the country."

Areas traditionally viewed as affordable, such as south-west Sydney, the Blue Mountains and the Central Coast, are now beyond the reach of most renters on low incomes due to the steep rise in rental prices.

"People who can't afford to buy houses now are staying in the rental market," Ms King said. "That's creating a demand which is pushing up rental prices and squeezing out renters on lower incomes."

Figures from the ABS show an increase in the proportion of tenants, with 26 per cent of the population renting from a private landlord in 2013-14, compared with 18 per cent in 1994-95.

Single people and Baby Boomers approaching pension age are particularly vulnerable in the rental market, Ms King said.

"They can end up spending a huge proportion of their income on rent," Ms King said.

"The result is they don't have enough money for bills or food. It's one of the reasons we see people coming though our emergency relief centres. People would rather go without food than risk losing their home."

The Anglicare report found no affordable suitable homes for single people on Newstart, Disability or Youth Allowance payments and just eight for single people on the age pension.

Only 24 properties were affordable and suitable for single minimum wage-earners with no dependents.

Anglicare is advocating for a boost to the number of social and affordable properties in NSW, saying 20,000 social housing dwellings are needed by 2025, in addition to the homes already planned by the state government under the Social and Affordable Housing Fund and its Communities Plus program.

"If we're serious about taking the pressure off the private rental market, we have to increase the supply of social housing," Ms King said.

The Australian Council of Social Service (ACOSS) is lobbying the federal government to tackle affordability in the May 9 budget.

"We have become a nation of housing haves and have-nots," ACOSS chief executive Cassandra Goldie said.

"The housing 'haves' bought their first home years ago and many have investment properties as well.

"The housing 'have-nots' are the 800,000 low-income people paying more than 30 per cent of their income in rent, who know they could lose their home at the end of the 6-12 month lease."