Holiday meals — with all that delicious butter, cream and gravy — can leave you feeling stuck to the couch. The grease and oil can wreak havoc on our sewer systems too, when they combine with trash to form something called a fatberg.

Journalist Jessica Leigh Hester wrote a chapter on fatbergs in her new book, “Sewer.” 

“One way that someone described it to me was that gloopiness begets more gloopiness,” Hester said. “So once you have this sticky surface, more things are likely to glom onto it.”

The bigger and gnarlier these accumulations get, the more likely they are to clog up sewer pipes, leading to backups and the production of dangerous gases. Hester said fatbergs are the No. 1 problem she heard from sewer workers across the U.S. — and around the globe — while researching her book. 

Our sewers were simply not built to carry away fat, grease and trash, Hester said. 

“They are, I guess, like many humans, stretched too thin, overtaxed, doing way more than they thought they would be enlisted to do when they signed up for the job,” she said. 

But we — the waste-producing overlords — don’t often think about our sewers, said Mark Kawamoto, environmental protection manager at the Orange County Sanitation District in Southern California. 

“We’ve always had this perception, the sewer is this magic black hole,” Kawamoto said. 

Still, the sewers Kawamoto oversees in California’s third-most-populous county are less taxed than they used to be, he said. That’s, in part, because of rules put into place in the early 2000s that require restaurants to install grease traps and recycle used cooking oil or dispose of it in waste bins. 

But new problems keep cropping up, like baby wipes, makeup wipes and cleaning wipes — some of which are supposedly flushable. These wipes can form the foundations of fatbergs, and they became especially popular during the pandemic. 

The National Association of Clean Water Agencies, which represents public wastewater and stormwater services, estimates that wipes in the pipes cost these agencies about $441 million a year. They also make it harder to recycle wastewater, Kawamoto said.

“So it’s becoming more and more critical that people need to be cautious about what they actually send down the sewer.”

California and several other states have passed legislation in recent years requiring wipes with plastic fibers to carry a “Do not flush” label. There’s similar legislation in Congress too. 

As for fatbergs, wastewater champions hope that greater public awareness will reduce the amount of fats, oils and grease — also known as FOGs — that people pour down their drains at home. The city of Santa Ana in Orange County gives out glass jars to store hot grease until it cools and can be scooped into the trash as well as food scrapers to get the scraps off plates before they hit the garbage disposal. 

“Ideally, garbage disposals should be used for that food that kind of makes it past all those checkpoints,” said Robert Hernandez, water quality supervisor for the city of Santa Ana.

Hernandez said the city also sends out extra reminders to residents about proper grease disposal around this time of year. 

“Our drains work overtime during the holidays because many people are spending more time at home doing a lot of cooking,” he said.

Fatbergs have become a sort of cultural antihero. Illustrator Nathan Wright has written fatberg comic books, there’s a potential fatberg Lego set in the works and even a fatberg song by artists Willie Gibson and Helen McCookerybook.

As you sit down for that special meal, here’s to a holiday without fatbergs.