The Hidden Environmental Footprint of a Full-Service Restaurant

We wanted to do something different than our usual informational content. Over the past few weeks, we’ve been researching and gathering credible data to understand better the hidden environmental footprint of a typical restaurant, not just in terms of food waste, but also in the water they use, the grease they generate, and the oil they dispose of. What we discovered was eye-opening. The numbers tell a powerful story, and we’ve combined those findings into a report that’s designed to help business owners, sustainability advocates, and industry professionals grasp the true scale of restaurant waste and what can be done about it.

Water Use and Wastewater Discharge

A typical full-service sit-down restaurant uses enormous amounts of water on the order of 3,000 to 7,000 gallons per day, with an industry average around 5,800 gallons daily. Over a full year, that’s more than 2 million gallons of water consumed (and roughly that volume sent down the drain as wastewater). To put 2 million gallons in perspective, one restaurant’s yearly water waste could fill about 3 Olympic-sized swimming pools or nearly 30,000 bathtubs. In other terms, a single restaurant’s annual water use is equivalent to the annual water usage of roughly 18 American homes.

Most of this water usage becomes wastewater that must be treated. Kitchen and dishwashing operations account for about 52% of a restaurant’s water use, and restrooms account for another 31%  all of which end up in the sewer system. Thus, the average restaurant discharges on the order of 2 million gallons of wastewater per year – water that carries food scraps, detergents, and other contaminants into municipal treatment plants. This high volume of greasy wastewater contributes significantly to the load on local water treatment infrastructure. Fats, oils, and grease in restaurant wastewater are a leading cause of sewer blockages, implicated in nearly half of reported sewer clogs.

Environmental impact

The water footprint of one restaurant is staggering. It represents 15% of total water use in the entire commercial/institutional sector nationally and drives up utility costs and energy use (since much of the water is heated). During droughts, some regions have imposed strict measures on restaurants (for example, California requires restaurants to serve water only on request and mandated a 25% cut in water use during its 2015 drought). Reducing water waste through efficient fixtures (e.g., low-flow pre-rinse spray valves, high-efficiency dishwashers) can save thousands of gallons. For instance, simply upgrading a spray valve saved a Boston cafeteria 48,000 gallons per year (a 63% reduction). The bottom line: each restaurant’s water/wastewater output is massive on the scale of municipal swimming pools and offers a big opportunity for conservation.

Used Cooking Oil (Yellow Grease) Output

In addition to water waste, restaurants generate large quantities of used cooking oil (also called “yellow grease”). A full-service American restaurant that does any frying will produce hundreds of gallons of waste cooking oil in a year. One study found that an “average-sized restaurant or cafeteria” disposes of roughly 30 gallons of used cooking oil per month (≈360 gallons per year). However, this varies hugely by cuisine and volume – for example, a busy fast-food restaurant generates about 35 pounds of used fryer oil per day. That works out to roughly 12,775 pounds per year (≈1,600 gallons of oil annually). In fact, across all U.S. quick-service restaurants, it’s estimated that 249 million gallons of used cooking oil are produced each year. Including full-service restaurants and institutional kitchens, hotels and restaurants in the U.S. generate about 3 billion gallons of waste cooking oil annually.

Thankfully, most restaurants are required to recycle their used cooking oil instead of dumping it. Disposing of fryer oil down the drain is illegal due to the damage it causes to plumbing and sewers. Restaurants typically store used oil in leak-proof containers or barrels for pickup by licensed grease recycling companies. The environmental upside is that this “yellow grease” can be refined into biodiesel fuel. One gallon of used cooking oil can yield roughly one gallon of biodiesel after processing, which can be used in place of petroleum diesel. Biodiesel made from used cooking oil can reduce greenhouse gas emissions by around 86% compared to regular diesel. Major biodiesel producers rely on restaurant grease as a feedstock – for example, the U.S. collected about 0.85 billion gallons of used cooking oil in 2022 for biofuel and other uses.

What is the scale of one restaurant’s oil waste in relatable terms?

Consider: if a mid-size restaurant produces ~400 gallons of used oil in a year, that could be converted into ~400 gallons of biodiesel, enough to fuel a diesel box truck for over 3,000 miles. Multiply that by thousands of restaurants: the 3 billion gallons of used cooking oil from U.S. food businesses each year is enough to fill tanker trucks lined up from San Francisco to Washington D.C. and back. The hidden energy content in restaurant oil waste is huge, and recycling it into biofuel helps offset a portion of our fossil fuel use. On the other hand, if not properly collected, used oil can wreak environmental havoc; it can congeal in sewers (forming “fatbergs”), contaminate waterways, or end up in landfills, where each gallon of rotting oil can pollute thousands of gallons of groundwater. This is why 82% of restaurants now participate in oil recycling programs and why many cities and states have strict grease recycling mandates.

Grease Traps and FOG (Fats, Oils, Grease) Waste

Aside from fryer oil, restaurants also generate “brown grease,” the fats, oils, and grease that wash off dishes, griddles, and pots and go down the kitchen drains. To prevent this gunk from clogging sewer lines, restaurants use grease traps or interceptors: plumbing devices that capture FOG from wastewater. A typical full-service restaurant will have either a small indoor grease trap (e.g., 20–50 gallon capacity under the sink) or, more often, a large in-ground grease interceptor outside (often 500 to 1,500+ gallons in capacity). As greasy wastewater flows through the trap, oil floats to the top and food solids sink, allowing cleaner water to exit to the sewer. Over time, the trap accumulates a layer of semi-solid grease and food sludge that must be pumped out and disposed of.

How much “grease waste” does one restaurant produce? It can be substantial. The EPA estimates that the combination of collected grease trap waste plus the FOG that still slips through into sewers ranges from about 800 to 17,000 pounds per year per restaurant. That upper figure suggests a high-grease establishment might generate 8.5 tons of FOG waste in a year, roughly equivalent to 2,000+ gallons of greasy sludge needing disposal. Even a more average output of 5,000 pounds/year would be on the order of 600 gallons of trap waste annually per restaurant. This brown grease is much less recyclable than fryer oil; it’s often contaminated with food particles and water. Specialized processors can convert some of it into biofuels or tallow, but much ends up as biosolids or landfill material.

The greater environmental importance of grease traps is in keeping FOG out of sewers, where it can cool and congeal on pipe walls. Cities spend millions of dollars annually unclogging fat buildup in sewer lines. In extreme cases, giant “fatberg” blockages (composed of cooking grease and wet wipes) have caused sewer overflows and required expensive removal operations.

Maintenance and regulations: 

Because of the risk, health and sewer authorities strictly enforce grease trap maintenance. Most municipalities require traps to be cleaned at least every 90 days (quarterly) or sooner if the trap is 25% full of grease/solids. High-volume restaurants often need more frequent service (many large interceptors are pumped every 4–8 weeks, and small indoor traps may be cleaned monthly in busy kitchens). Failure to maintain traps can result in overflows, foul odors, health code violations, and hefty fines. By routinely pumping the grease, restaurants not only avoid these issues but also protect local waterways, keeping grease out of sewage, preventing backups and overflows that can spill pollution into streams or streets.

It’s worth noting that grease trap waste is part of the hidden pollution footprint of dining out. The collected sludge from traps must be hauled by vacuum trucks to treatment facilities. Some cities are experimenting with FOG-to-energy programs (e.g., feeding collected grease into anaerobic digesters or biofuel plants) to put this waste to use. But more often, trap grease is de-watered and disposed of as solid waste. This represents a lost resource and an extra environmental cost of our food system. Simply put, every fried meal has a “grease footprint” beyond the plate – and across thousands of restaurants that adds up to tens of millions of gallons of gross waste that needs careful handling each year.

Putting It in Perspective

The annual waste outputs of a single restaurant are eye-opening when scaled up:

• Water/Wastewater: ~2,000,000 gallons/year per restaurant. One restaurant’s yearly wastewater could fill 3 Olympic swimming pools or nearly 30,000 bathtubs. Multiply by hundreds of restaurants in a city, and you’re talking billions of gallons of dirty water. Restaurants and hospitality businesses account for about 15% of all commercial water use in the U.S. Reducing this usage has big environmental benefits conserving water and cutting the energy used to heat and treat it.

  
  

• Used Cooking Oil: On the order of 300–1,600 gallons/year of fryer oil waste per restaurant, depending on the type of restaurant. A typical sit-down restaurant might produce enough waste oil to fill a home heating oil tank a few times over each year. Across the country, the 3 billion gallons of used cooking oil from food service could produce 3 billion gallons of biodiesel – which, in theory, could fuel millions of vehicles or provide renewable heating for cities.

  
  

• Grease Trap FOG: Roughly 0.5 to 2+ tons of grease and food solids captured per

  restaurant yearly (which is hundreds to a couple thousand gallons of brown grease slurry). The annual grease trap waste from one busy restaurant could weigh as much as a large SUV. Cities like New York have tens of thousands of food establishments, so one can imagine the mountain of grease generated citywide. This is why municipal FOG programs are crucial: by enforcing grease trap maintenance, cities prevent “fatbergs” and sewer overflows, protecting water quality.