Minnesota cities are declaring war on flushable wipes, fighting damage awards to homeowners victimized by a rising tide of sewer line backups.

State law has long held that cities aren’t responsible for foreign objects in the sewer system. But the popularity of flushable wipes has forced cities to defend themselves aggressively against homeowners who seek payment for damages from sewer backups caused by wipes and other “rags,” as they’re called in industry lingo.

“These disposable wipes seem to have grown and multiplied,” said Bob Cockriel, Bloomington utilities superintendent. “If we were to say the city should be paying for [damages], then that’s money coming from taxpayers.”

Bloomington is fighting to overturn a $15,000 judgment awarded to a city couple after a sewer main backup left “three inches of feces, urine, sanitary products and sludge” in their furnished basement on New Year’s Eve, court filings stated.

“It stunk like sewage in our home for three months,” said Kevin Isensee, who lives on Rich Road. “It doesn’t seem fair. I could see if it happened from our house to the street, but this was in the street.” Bloomington voluntarily paid $1,589 for a cleanup service at the Isensee residence, but the couple later won a judgment in conciliation court.

The city quickly appealed and asked for the case to be dismissed, saying the backup was caused by “roots and rags” that it’s not responsible for. The city doesn’t claim the Isensees caused the clog, but maintains that rag clogs aren’t its responsibility — no matter who caused them. A hearing in the case is set for Sept. 10 in Hennepin County District Court.

Earlier this year, the city of Wyoming sued six makers of wet wipes in federal court. The suit alleges that the so-called “flushable” wipes don’t break down after flushing. Instead, they clog pipes and pumps, forming huge white clumps that sewer workers have dubbed “polar bears.”

The League of Minnesota Cities often defends its 902 members in legal disputes. Peter Tritz, administrator of the league’s Insurance Trust, said claims against cities from sewer backups have increased in recent years.

“It’s fair to say there are more claims from backups,” Tritz said. “I would describe it as a problem that has grown over the last few years. But if these things are introduced into the lines, there’s really no way for the city to safeguard against it.”

In the Bloomington case, the city said that it examines every one of its 334 miles of sewer mains on closed-circuit television every 18 months. The industry standard, the city said, is once every five years. The city also “jets” its mains regularly, cleaning them with blasts of high-pressure water. The main that clogged on the Isensees’ street was jetted every year from 2010 to 2013, according to court documents.

The city even produced an educational video for its website called “Keep the Wipes Out of the Pipes.” In the video, a Bloomington utility supervisor cautions residents that “poop, pee and paper” are the only things that should be flushed down the toilet.

“I completely empathize with people when this happens,” Cockriel said. “But as long as the city … has been doing what it’s supposed to be doing, then the blame goes back to somebody who’s not doing what they’re supposed to be doing.”

Tell that to Isensee, who said he didn’t do anything wrong, either.

“We’re not lawyering up or anything,” he said. “We’re just going in and saying, ‘Here’s what happened. At least fix the problem.’ ”