Only in the past decade have grownups seized upon moist “flushable” wipes similar to those that clean baby bottoms, a product that has become a prized asset in a flat market. Accelerating sales are demonstrated inside the world’s sewers, where tons clog equipment. From New York to London, the hygiene fad costs governments millions of dollars a year.

As profit drive collides with the public’s interest in functional wastewater infrastructure, officials are discussing regulation and how to assess the cost of ungunking the system.

At stake is nothing less than “the long-term viability of the product category,” said David Rousse, president of the Association of the Nonwoven Fabrics Industry, a Cary, North Carolina-based trade group that represents manufacturers.

Wastewater officials in New York and other cities say products advertised as flushable aren’t, and that adults use products such as baby wipes that are too resilient to dissolve.

New York City, which runs the largest U.S. sewer system, has spent more than $18 million during the past five years replacing and repairing sewer-plant pumps, gears, valves and screens clogged when the cloth-like material didn’t disintegrate.

“A growing number of adults think that if it’s good for baby, it’s good for them,” said Vincent Sapienza, deputy commissioner of the city Department of Environmental Protection. “Many brands may say they’re flushable, but they wind up in our sewer plants fully intact.”

London’s Fatberg

Wipes compose about a third of the debris choking screens and pumps in U.S. treatment plants, and about 30 percent were sold as flushable, said Cynthia Finley, director of regulatory affairs for the National Association of Clean Water Agencies in Washington.

In New York, the city must pay workers to pull the stuff off screens and pumps and to cart it to landfills. Residual material extracted increased to more than 40,000 tons last year from 21,000 tons in 2008, Sapienza said. That’s about a thousand subway cars.

The globs aren’t unique to New York, which processes 1.3 billion gallons of waste a day. In London, a 15-ton wad of wet wipes and cooking grease last year accumulated to the size of a yellow school bus inside a sewer line, preventing neighborhood toilets from flushing. It took more than three weeks for Thames Water Utilities Ltd. to break up the “fatberg.”

Swirling Away

Similar blockages have been experienced in Orange County, California; Columbus, Georgia; and Vancouver, Washington. Portland, Maine’s Water District is still paying for the $4.3 million it borrowed in 2009, an amount almost equal to half its annual operating costs, for screens to catch wipes before they ruin pumps. In Canada, the Municipal Enforcement Sewer Use Group, an association of 25 communities, estimated wipes clogs cost the public at least C$250 million ($230 million) a year.

Sales of moist flushable wipes are a souce of sales growth in the household paper-products industry, rising 23 percent to $367 million from 2008 to 2013, according to Mintel Group Ltd., an international market-research firm.

“The average consumer believes if a product clears their toilet bowl, it’s flushable,” said Jamie Rosenberg, a Chicago-based household and personal-care analyst for Mintel. “People in their homes have no idea what’s going on downstream.”

Cheeky Question

Sales have grown thanks to frank and funny advertising, Rosenberg said. He cited a commercial for Kimberly-Clark Corp.’s (KMB:US) Cottonelle Flushable Wipes featuring British television personality Cherry Healey, who asks strangers in a U.S. airport, “How do you like to wet your bum?”

As wastewater officials become vocal, manufacturers such as Kimberly-Clark andProcter & Gamble (PG:US) Co. have played defense.

“We have invested significant time and resources to understand the difficult issues faced by agencies that process wastewater and to develop technologies to make sure that flushable wipes sold by K-C will be considered flushable,” said Eric Bruner, a Kimberly-Clark spokesman.

The company is part of a task force organized to work with a group of municipal wastewater authorities to quantify how much of the clogging is due to flushable wipes. The group will also develop labeling standards.

“The biggest culprit is baby wipes designed to be wrapped up in the diaper and thrown out in a bin,” Rousse said in an interview.