Elderly and disabled people in parts of Wales are waiting up to two years for money to pay for essential home aids like hand rails.
In some areas, people are waiting four times longer for the grants.
Newport council took an average of 638 days to pay the Disabled Facilities Grant (DFG) last year compared to Merthyr Tydfil council's 175 days.
Wales' Older Peoples Commissioner said it was unacceptable. Newport council said it was making improvements.
A DFG is a local council grant that helps towards the cost of adapting someone's home.
In Wales, the maximum available amount is £36,000 which can be spent on lifts, ramps, widening doors, installing a downstairs bathroom or improving a heating system.
The average time it took to pay out grants in Wales was 326 days last year.
Brenda Rowley, 84, a retired headmistress from Newport, had rails installed in her home after a fall.
Her case was taken up by a charity, which meant she avoided a long wait, but she lives in an area where some people have to wait up to two years for adjustments.
"I'm trying to think how I would manage if it hadn't been dealt with," she said.
"Going up and down those stairs without the hand rails, now I couldn't do it at all but even then there was a danger and I'd have to be careful.
"Having it done was, from a safety point of view, paramount."
Last week, Sarah Rochira, the Older People's Commissioner for Wales, said she would take public bodies, including councils to court, if they fail in their obligations to Wales' 710,000 older people.
She described the figures as a postcode lottery, completely unacceptable and a failure in public service.
"I don't think 700 days is acceptable," she said.
"I think we can get it right and we need to get it right, and I want to work in partnership with local authorities to make sure we do.
"But, if the only way that we can get it right is lay down guidance and use my statutory powers, then as commissioner that is what I will do."
BBC Wales understands Mrs Rochira has already written to councils for Powys, Vale of Glamorgan, Flintshire, Torfaen, Ceredigion, Neath Port Talbot and Newport expressing her dissatisfaction that it took over the 12 month statutory period to pay the grants.
Experts say an average grant of £7,500 can keep someone out of residential care for four years, which can cost over £100,000.
The WLGA says that the average time to deliver a grant has reduced, and that some adaptations are complex and expensive.
It accepted that it was crucial DFGs were delivered in a timely manner.
Newport council said it accepted that the time it takes to process the grants has been far too long, but it says it is putting improvements in place and average waiting time is down from its 630 days.
A council spokesperson said: "Earlier this year the council approved a series of measures to help tackle the backlog of applications for adaptations to people's homes.
"Disability facility grants (DFGs) are given to help people remain living independently in their own homes. Over recent years demand for these grants has increased substantially.
"The council is also looking to add extra capital budget to particularly address the backlog of DFGs."
The spokesperson added changes to policy include offering loans rather than simply grants and using the equity in people's homes as security for the loan.