As the lunch hour faded on a recent workday, Ed Hairfield and his crew roared into the parking lot of a Panda Express.

They stood a few feet from the Hyattsville, Md., restaurant’s door, where mouth-watering aromas drifted out each time it opened. But the crew of one of the Washington, D.C., area’s largest sanitary systems could not care less about the menu’s SweetFire Chicken Breast. They only cared about the lard.

Every day, up to five times a day, Hairfield’s six-man Washington Suburban Sanitation Commission crew pops open a hatch next to a store or restaurant to study a nasty sight: lumpy grease buildup from cooked animal and vegetable fat.

It’s the same stuff that makes flabby bellies jiggle and roll, that clogs arteries and stops hearts, and the crews are deployed to keep it from doing the same to WSSC’s network of sewer pipes. This year and last, inspectors issued 31 citations to pizza joints, Chinese restaurants, cafes and other establishments for failing to properly maintain pricey interceptors that stop thick kitchen grease from backing up pipes.

But the blame doesn’t fall solely on restaurants. Grease is poured down kitchen drains by hundreds of thousands of household cooks in the region, and by hundreds of millions of people nationwide. Coagulated fat from fried bacon, steaks, chicken, burgers and potatoes cools into a pipe-choking yellowish blob after flowing into sewers, causing serious overflows that threaten homes and the Chesapeake Bay.

Around Thanksgiving, WSSC officials brace themselves, commission spokeswoman Lyn Riggins said. That’s when thousands of people deep-fry turkeys and pour tubs of lard down drains. Last year during the holiday, WSSC ran public service announcements in theaters before movies on the proper way to dispose of grease at home.

“People are using the sewer system as an alternative trash can, a very expensive alternative. Grease and food scraps are being sent down the sinks; disposable products, especially baby wipes and public restroom paper towels, are being flushed down the toilet,” said Robert Villée, a committee chairman for the Water Environment Federation.

Grease plays a starring role amid the other junk, Hairfield said. “When you put grease on top of onion skins, potato skins and all that other stuff, it’s like glue. It sticks to the pipes.”

In the extensive and poorly funded American sewer infrastructure, with pipes as old as the Gettysburg Address in many places, grease from commercial operations and households is causing up to 40 percent of sewer overflows nationwide that back raw sewage into sinks and bathtubs and into local waterways.

The presence of fat in the bowels of cities and suburbs is just one symptom of a more pressing problem in the nation’s old and decrepit sewers, said Adam Krantz, managing director of governmental affairs for the National Association of Clean Water Agencies.

“We are facing a looming crisis in terms of our water infrastructure,” Krantz said. “We are nearing the 40th anniversary of the Clean Water Act in October, and we are seeing some pipes and treatment systems nearing the end of their useful lives.”

Money used by utilities to upgrade facilities and cut down on overflows to meet Environmental Protection Agency regulations could buy larger and more efficient pipes that can overcome grease, tree roots and other problems.

But the estimated pricetag for fixing the nation’s new water infrastructure over the next 20 years is steep — $334 billion, according to the EPA. So cash-strapped utilities are making do with what they have, relying on patchwork.

“If we could reduce one tablespoon of grease per household, that’s 57,000 gallons of grease we wouldn’t have to deal with,” said George Martin, general manager of a sewer system in Greenwood, S.C.

Martin spoke as if his proposition were a fantasy, and Villée knows why: “No one’s coming to arrest you for this one.”