During one of his jobs, he said a customer had been left shocked after finding a rat swimming in her toilet bowl.
“She’d been using the bathroom and heard a noise. She looked down and it was in the toilet bowl. And this is happening more and more frequently,” he told the Norwich Evening News.
“They used to work around us but now they’re gaining access they wouldn’t have attempted before.”
Mr Dellbridge added that the issue had been worsened by “overflowing bins” and his firm had been forced to take on extra staff to deal with the rodents.
He continued: “Because of the throwaway culture we have the rubbish is just piling up and feeding them.
“Rats are letting themselves into people’s houses and businesses.”
A spokeswoman for Norwich City Council said: “Try not to feed your pets outdoors, if you do, make sure you’re present when feeding them, and remove any remaining food afterwards.
“People that have seen rats near their property should avoid feeding wildlife as this is a food source for rodents too.”
Ace Pest Control have urged Britons to keep their toilet seats down and ensure windows and garage doors don’t have holes in them to prevent rodents entering their property.
Mr Dellbridge’s warning comes after a pest control agency warned last year that coronavirus lockdowns could create a “perfect storm” for rat infestations in homes.
The largest rat believed to have been caught in Britain measured 21 inches from tip to tail and was found in a property in Bournemouth in November 2018.
Terry Walker, a pest control expert who caught the rodent, said that rats were becoming bigger because humans were creating “more waste” and “the type of waste we are throwing away is fattier”.