Cuts to household bin collections have led to an increase in people dumping rubbish in fields and on council estates, it has been claimed.
In Bridgend, where a two-bag limit was introduced in 2017, fly-tipping levels are at their highest level in a decade.
Residents living on the Wildmill estate said the rest of the county was using their estate as a "landfill" site.
But the council said most residents had embraced efforts to limit waste and increase recycling.
Official statistics show the total number of reported fly-tipping offences in Wales fell to 35,076 last year, the lowest recorded figure since 2014-15.
But analysis of the figures showed Conwy, Flintshire, Carmarthenshire, Merthyr Tydfil and Blaenau Gwent all recorded record levels of dumping last year.
Incidents involving fly-tipping of black bags - rubbish which should go in the household waste bin - also increased in areas where bin collections have been changed.
Merthyr Tydfil council said it was having issues with people dumping black bags next to bins in cemeteries and parks.
While recycling rates have improved since controversial bin changes were brought in, the number of black bags being dumped illegally has almost quadrupled.
In 2015-16, before a trial of monthly bin collections was brought in, 129 black bin bags were fly-tipped, the following year this had increased to 282.
And by the end of March 2019, when the pilot was rolled out across the whole county, the figure stood at 416.
The county has been judged one of the cleanest places to live in Wales, and recorded its highest street cleanliness rating in 10 years, last year.
But one resident said, since the changes, people had been dumping bags in public litter bins and on industrial estates. Others said charges at tips had let to an increase in fly-tipping.
Another resident said she had her locks broken on her bins twice by fly-tippers and had to pay a private contractor to take the waste away.
Cabinet member Greg Robbins said there was no excuse for fly-tipping as most households were managing fine with the monthly collections.
In Bridgend, residents said there has been an increase in fly-tipping since changes to bin rules.
The system, introduced in 2017, limited homes with fewer than five occupants to throwing out just two bags of non-recyclable rubbish every fortnight.
But figures show there were 1,937 reports of fly-tipping last year - the highest level in more than a decade.
The number of black bags filled with household waste being fly-tipped has increased by almost 200% - from 297 the year before the changes were introduced, to 873 last year.
On the Wildmill estate, where about 1,000 people live, residents said people were coming from across the county to dump their bags.
The estate has communal bins for recycling, and boxes with blue crosses on for bags to be collected - but residents said people were coming from miles away to dump their bags onto the piles, leaving litter strewn everywhere.
Rachel Nicholls said she was sick of living in a "rat-infested hole" and living in a "landfill" site for the rest of Bridgend.
"Everybody else is treated like a person, but here in Wildmill we are treated like second-class citizens," she said.
"We have pride in where we live, everyone knows they are fly-tipping but they don't care."
But the council said its investigations showed the vast majority of fly-tipping in Wildmill originated from residents.
"Bridgend County Borough was recently confirmed as having the second-highest recycling rate in the UK, and the success of this ultimately lies with how the vast majority of local residents have embraced efforts to limit waste and increase recycling," a spokesman said.
Merthyr Tydfil council replaced every 240-litre bin with slim-lined 140-litre models, after being judged one of the worst areas for recycling in Wales.
Some residents complained they were too small to fit all their rubbish in.
Looking at figures, last year the number of illegally-dumped black bin bags hit an all time high, with 1,010 incidents recorded.
This has increased year-on-year since the changes were introduced in 2015.
The number of incidents of household items, such as fridges, being dumped also reached record levels last year.
Gelligaer and Merthyr Common has been a hotspot for people to dump their waste for years.
The ranger there said residents had noticed a spike in fly-tipping after changes to the tip - but this had since improved.
He said they were hoping to get ditches dug at the side of roads to stop people being able to dump on the common.
Merthyr Tydfil council confirmed there had been a spike in black bags being collected by fly-tipping teams, and it was having issues with bags being dumped in cemeteries and parks.
In 2015 there were protests when Blaenau Gwent moved to a new bin collection system.
It limited black bin collections to once every three weeks and introduced "Troliblocs", a stack of three recycling boxes on a wheeled trolley.
And in June 2018 it introduced a "no side waste" policy, with a black bag sorting system introduced at its household waste recycling centre.
According to figures, the number of black bags being fly-tipped went from zero in 2015-16 to 107 in 2016-17, hitting an all time high of 170 last year.
Overall fly-tipping reports have increased every year since 2015-16 and are now at an all time high.