For many foodies, nothing delights the senses like a sizzling wok in Flushing or crackling tacos al pastor in Jackson Heights. But there's a downside to the smorgasbord: So much used cooking oil is poured down the drain that sewers in Queens regularly experience the municipal equivalent of cardiac arrest.

Some section of the city's 7,500 miles of sewer lines gets blocked virtually every day, and discarded cooking oil is the reason 60% of the time. But in parts of Queens, that grease is the culprit in nearly 80% of all sewer backups, a problem that is especially acute near Kennedy Airport.

Experts say one reason Queens' sewers get blocked so often is that a lot of food is prepared in the city's most diverse borough, where residents, who hail from 120 different countries, might not be familiar with the best grease-handling practices.

"Just about everyone has dumped used cooking oil down the drain at one time or another," said David Balkan, chief executive at Balkan Plumbing in Richmond Hill, Queens. "It cools and congeals in the sewers, where it will block anything and everything."

In an effort to educate the public on the ills of grease dumping, last year the city enlisted interns from the Summer Youth Employment Program to knock on neighborhood doors as part of its Cease the Grease campaign. The teenagers visited more than 50,000 Queens households and 1,000 restaurants to remind people that used cooking oil and fat should be sealed in nonrecyclable containers and thrown out with the rest of the trash, not poured down the sink.

But grease has been blocking big city sewers practically since the pipes were laid. In 1859, a Brooklyn sewer commissioner observed that "melted grease is very objectionable." Two years ago in London, an 11-ton mound of congealed fat was extracted from a sewer, requiring more than $600,000 in repairs.

To minimize such costly damage, New York officials have encouraged restaurant owners to sell their used cooking oil to firms that convert it into biodiesel that fuels garbage trucks and other municipal vehicles. There are 24 licensed grease haulers in the city, according to the Business Integrity Commission, which regulates the industry. In October those haulers got a boost when Mayor Bill de Blasio signed a law requiring that the biodiesel content in the city's heating oil supply increase to 20% in 2034 from the current mandate of 2%.

That legislation could provide a lifeline for grease haulers, who have struggled financially in recent years after the steep drop in crude-oil prices chilled demand for their product despite the environmentally friendly nature of their services. Grease Lightning, a Manhattan-based hauler, slipped into bankruptcy and was liquidated last year. Edward Taylor, who runs a fish distributor in the Bronx's Hunts Point market, said that during the summer a vendor simply stopped picking up his used oil because it became impossible to sell at a fair price. The market value of used cooking oil fell to less than 20 cents per pound in New York last year, a better than 50% drop since 2011, according to the Jacobsen market-research firm in Chicago.

Used cooking oil is not only bad for sewer health, it's also useless to recyclers once it gets into the pipes and mixes with plastics and other garbage, said Bob Adamski, a former city sewer chief. Only yellow grease, the stuff used in deep fryers, is readily convertible into biodiesel. Brown grease, which is basically anything used in a pot or pan, has no market value unless it is refined by a firm such as United Metro Energy, a Brooklyn company that is owned by former mayoral candidate John Catsimatidis. Trap grease, the icky assemblage of oily food scraps and water, typically isn't repurposed for humans but is sometimes used for various pet foods, according to Adamski.

A little grease is a big problem

Grease causes sewer backups all over the city, but they most commonly occur in certain Queens neighborhoods including South Jamaica and St. Albans, where more than 4,800 complaints were made in the past five years, an average of nearly three per day. The city received almost 15,000 reports of greasy sewer clogs during that time, according to 311 call logs—numbers that suggest one-third of the most mucked-up city sewers are located in neighborhoods that house less than 5% of New York's 8.5 million residents.

Although some of those sewer problems can be linked to the vast amounts of cooking oil used in preparing dishes such as deviled fish, a deep-fried delicacy on the menu at many Sri Lankan restaurants in southeastern Queens, experts say the chronic backups mostly reflect the area's history and geography.

Sewer pipes in southeastern Queens tend to be 10 inches in diameter, Adamski said—less than half the typical size in other boroughs—because they were installed decades ago, when the area was relatively undeveloped. Southeastern Queens is also a flood basin, so its streets and basements are vulnerable to sewer backups after even modest rainfalls. The problem's origins go back to the 1940s, when a natural drainage area was paved over to build runways for JFK. Moreover, the area's groundwater table has steadily risen during the past decade or so. Climate change is a factor, and so is the fact that the city no longer pumps the ground wells that once provided the area's drinking water.

The city Department of Environmental Protection has pledged to spend $6 billion on a comprehensive sewer system overhaul for southeastern Queens, and it already has upgraded Springfield Gardens and other areas. But plenty of work remains to be done. And when pipes are under such stress, dumping even a little used cooking oil or animal fat can easily trigger another obstruction.

"When you've got sewers as overburdened as they are in Queens," York College earth sciences professor Ratan Dhar observed, "a little grease goes a long way."