As superintendent of Crystal's Public Works Department, Patrick Sele has seen lots of items flushed down the toilet over the years: diapers, dental floss, hygiene products.

But mop heads?

"That's a new one for us," he said. "I'm not sure how they fit down a 4-inch line."

At least four times in recent weeks, mop heads have ended up in the city's sewer system and clogged pumps at the lift station. The contraband is believed to be coming from households in neighborhoods south and west of City Hall, Sele said.

The city has previously had problems with people putting flushable wipes down the toilet, but the mop heads are "unique," he said.

Items such as mop heads can get stuck in mains and block pipes. They also can get tangled in pumps, which could lead to sewage backups flowing into basements, Sele said.

So far, that has not happened because sharp city staffers have caught them before damage was done, he said. But the issue is serious enough that the city last week put out a plea on its Facebook page asking residents to stop it.

Sele said he isn't sure if residents are getting a jump on spring cleaning and not knowing they can't flush mop heads down the toilet.

"Anything moving through the sewer system could potentially cause a backup," he said. "Only toilet paper and bodily waste should be going down the toilet."

As part of its sleuthing efforts to find the culprits, the city has asked residents to call 911 if they see anybody other than city staff or utility workers opening a manhole cover, "especially if they are putting a mop head in the manhole," the city said.

Crystal is not the only place this has happened. Utility officials in Gainesville, Fla., put out a similar plea in 2019 after seven mop heads plugged its sewer system.

"It's been a consistent issue across the country," Sele said.

Tim Harlow • 612-673-7768