Almost half the 25,000 sewer blockages in Yorkshire last year were caused by wet wipes flushed down toilets, Yorkshire Water has said.
The company said 11,946 of the 25,976 blockages were caused by wipes which did not break down in sewers.
Yorkshire Water warned some wipes contained plastic which caused them to snag in pipes.
A spokesperson advised “only the three Ps – pee, poo and paper – should be flushed down the toilet”.
Wet wipe blockages could prevent toilets working, leading to sewage flooding properties, gardens or roads and could even cause the pollution of local streams and rivers, the company said.
A spokesperson said other causes of blocked sewers included construction debris, “foreign objects” ranging from tennis balls to bank cards and dolls, fats and oils poured down drains, and tree roots.
Mark Hammond, head of customer field services at Yorkshire Water, said: “Every day our teams deal with blockages caused by wet wipes, un-flushables and foreign objects in the sewer.
“This costs millions of pounds to resolve, money which could be better spent on investment in the wider network.”
Mr Hammond said he wanted people to “really consider” what they flush down the toilet and pour down the drains so the company could reduce the number of blockages it dealt with.