Two brothers who ran an illegal waste business caused an infestation of up to 500 rats after piling 120 tonnes of rubbish in their garden.
Conwy Council found mattresses, car parts and hundreds of bin bags of domestic waste at the Kinmel Bay home of Raymond and Ian Murray in May.
It spent £59,000 on the clean-up and used 165 rat traps – the equivalent used across the county in a month.
The brothers were given suspended jail terms at Mold Crown Court.
They admitted running a waste business without a permit.
A notice was served by the council to clear the mess from the two-acre garden in Gwellyn Avenue within 21 days but the brothers failed to do so.
Complaints were received from neighbours and a nearby caravan holiday park, which had to give refunds to customers affected by the rats, which the court heard numbered between 400 and 500.
Christopher Stables, prosecuting for Natural Resources Wales, said the defendants had set up a “completely unregistered waste transfer station” within their grounds in a residential area.
“There was clear evidence of a huge rat infestation with bags of domestic rubbish having been ripped open and rat burrows,” he said.
No environmental permit had been sought and it was extremely unlikely that one would have been granted, he added.
Sarah Yates, mitigating, said the business was properly run to start with but the brothers found it uneconomical to take the waste to a licensed site, so they began sorting waste at home and matters got out of hand.
She added that the defendants wanted to apologise to the community.
Judge Rhys Rowlands said custody was justified but handed down 10-month prison sentences, suspended for two years, and 200 hours of unpaid work.
He adjourned financial aspects of the case to be considered in May under the Proceeds of Crime Act.