As the end of the week rolls around, Albert Santos and his fiancee Jenny Armas have little left in the bank to get by.

After paying for groceries and bills, they then fork out almost half of their income on rent for an old two-bedroom apartment in Parramatta. Saving for their wedding, let alone a first home, is pretty much out of the question.

“We’re paying $430 a week, that’s more than $1700 a month, that’s about 40 to 50 per cent of our joint income, and we’re lucky it’s not much more,” Mr Santos, a freelance writer, said. Ms Armas is an occupational therapist.

Rental affordability in Sydney has fallen to a record low, with the average tenant spending 29 per cent of their household income on accommodation, pushing them towards the rental stress threshold of 30 per cent.

The latest Rental Affordability Index (RAI) shows great tracts of Sydney are out of reach for families on moderate incomes of $140,000.

A single parent earning $70,000 would struggle to rent an affordable two-bedroom home within 40 kilometres of Sydney’s CBD, according to the data to be released on Tuesday.

The executive officer of Australia’s peak housing body National Shelter, Adrian Pisarski, said Sydney was the least affordable part of Australia with no signs of improvement.

“It’s deteriorated further – we didn’t think that was possible in Sydney,” he said.

“The lower down the income scale you go, the worse it gets but even for moderate income earners, much of Sydney is unaffordable. Renters in Sydney are right on the threshold of disaster. The average renter is approaching housing stress.”

Ellen Witte, partner at SGS Economics & Planning which has compiled the index since 2015, said Sydney renters were being pushed further out to the margins, which affects commuting time, transport costs and access to healthcare and education.

“You do wonder how someone on a moderate income would find a place to rent,” she said.

“It really impacts people’s lives especially families with children who might have to change schools every time the family moves somewhere cheaper.”

Mr Santos, who is on a disability pension, said it was upsetting to see the once-working class suburb of Parramatta becoming increasingly unaffordable, as rising rents pushed more tenants into western Sydney.

“You’ve got people from Surry Hills and Redfern moving to Summer Hill and Ashfield, everyone there’s being pushed out to the likes of Parramatta and people from there are having to leave Sydney.”

Rents in regional NSW are not much more affordable than greater Sydney, with the data showing tenants in the rest of the state are paying 28 per cent of their income on accommodation.

“Historically, people could have moved to cheaper areas but in NSW there is almost nowhere to run, nowhere to move to – it’s hopeless,” said Ken Langston, head of government and sector relationships at Community Sector Banking .

“So you have to make tough choices about what you do with what little income you have left. Do we cut back on meals? Do we not see the doctor?”

Tenants NSW senior policy officer Ned Cutcher said renters comprised about one-third of households but were often overlooked by government policymakers.

“Rents are going up and wages are not. On top of that, renters have very little security of tenancy – they can be kicked out at any time,” he said. “This stuff keeps people awake at night.”