Most wasted food in the United States ends up in landfills. Food is the single largest category of material in municipal landfills, making up about 24% of everything buried there. With over 133 billion pounds of food wasted annually in the U.S. alone, the journey from trash can to final destination is worth understanding, because the endpoint determines whether that food becomes a climate problem or gets put to some remaining use.
Landfills: Where Most Food Waste Ends Up
The default destination for wasted food is a landfill. When your uneaten leftovers go into the trash, they’re collected by waste haulers, compacted into trucks, and dumped at a landfill site where they’re buried under layers of other garbage and soil.
What happens next is slow and surprisingly harmful. Buried food doesn’t decompose the way it would in a backyard compost pile. Landfills are dense, compacted environments with very little oxygen. In those conditions, microorganisms break food down through a multi-stage process. First, bacteria break complex organic material into simpler molecules. Then fermentation converts those molecules into alcohols and organic acids. Finally, a different group of microbes called archaea take over and produce methane, a potent greenhouse gas. This process can take years, and in dry sections of a landfill, food waste can persist for decades.
Methane from landfills is a major contributor to climate change. Some modern landfills capture a portion of this gas and burn it for energy, but many older or less-equipped facilities simply vent it into the atmosphere. The sheer volume of food reaching landfills makes this the most environmentally damaging disposal pathway.
Incineration and Waste-to-Energy Plants
Some food waste is burned in waste-to-energy facilities rather than buried. These plants combust municipal solid waste at high temperatures and use the resulting heat to generate electricity. Food waste burns less efficiently than drier materials because of its high water content, but it still contributes to the fuel mix. The process produces ash (sent to landfills) and emissions that are filtered before release. Incineration reduces the volume of waste dramatically, but it doesn’t recover any of the nutrients in the food.
Composting Facilities
A growing share of food waste is diverted to composting operations, where it breaks down aerobically (with oxygen) into nutrient-rich soil amendment. Industrial composting works much faster than landfill decomposition because operators actively manage the conditions. Piles heat up rapidly as microorganisms get to work. Decomposition is fastest when internal temperatures reach between 90°F and 140°F. Above 140°F, most microorganisms can’t survive, so operators turn the piles to regulate heat and maintain airflow.
The high-temperature phase lasts anywhere from a few days to several weeks. After that, temperatures gradually drop. When a pile falls below about 70°F, composting is nearly complete. The finished product is a dark, crumbly material used to enrich soil in agriculture, landscaping, and gardens. Cities like San Francisco, Seattle, and Portland have curbside food scrap collection programs that route organic waste to these facilities.
Anaerobic Digestion for Energy
Anaerobic digestion is an industrial process that intentionally harnesses the same methane-producing chemistry that happens accidentally in landfills. Food waste is loaded into sealed reactors where bacteria break it down without oxygen, producing biogas and a leftover solid-liquid material called digestate.
The biogas is 50% to 75% methane, which is the primary component of natural gas. Facilities can burn it on-site to generate electricity, clean it up to pipeline-quality natural gas, or use it as vehicle fuel. The digestate left behind is rich in nutrients and can be used as fertilizer or soil conditioner after further processing. Multiple types of organic waste (food scraps, animal manure, wastewater solids) can be combined in a single digester, a practice called co-digestion that improves efficiency.
Anaerobic digestion captures energy that would otherwise escape as uncontrolled landfill emissions, making it one of the more climate-friendly disposal options for food that can’t be eaten.
Animal Feed
Some food waste never reaches a landfill or processing facility because it’s redirected to animal feed. Breweries, bakeries, juice manufacturers, and food processors routinely send their by-products to livestock operations. The FDA requires that these by-products be held under sanitary conditions, stored in clean containers, and protected from contamination. When there’s a risk of harmful microorganisms, the material must be heat-treated, frozen, or otherwise processed to eliminate safety concerns before animals consume it.
This pathway works best for consistent, large-volume waste streams from food manufacturers. It’s harder to implement with the mixed, variable scraps that come from households and restaurants, though some regions have developed collection systems for commercial kitchen waste destined for pig farms and similar operations.
Food Donation and Recovery
The best outcome for surplus food that’s still safe to eat is getting it to people who need it. Food banks, shelters, and community organizations distribute millions of pounds of recovered food each year. The Bill Emerson Good Samaritan Food Donation Act protects donors from civil and criminal liability when they give food in good faith to nonprofit organizations for free distribution. Amendments passed in January 2023 extended those protections to “qualified direct donors,” including grocery stores, restaurants, caterers, agricultural producers, and universities, allowing them to donate directly to individuals in need without going through a nonprofit intermediary.
Despite these legal protections, donation captures only a fraction of edible surplus. Logistics remain the biggest barrier: perishable food needs refrigerated transport, quick turnaround, and organizations with the capacity to sort and distribute it before it spoils.
The Global Picture
Food waste is not just an American problem. Globally, 1.1 billion tonnes of food were wasted in 2022, according to the UN Environment Programme. About 60% of that waste happened at the consumer level (households), 27% at food service operations (restaurants, cafeterias, hotels), and 13% at the retail level (grocery stores, markets).
The pattern shifts by income level. In low- and middle-income countries, 81% of food waste occurs at the household level, partly because refrigeration and storage infrastructure are limited. In high-income countries, households still account for 53% of waste, but food service and retail contribute larger shares (27% and 20%, respectively). Regardless of where in the world it happens, the destinations are broadly the same: landfills and open dumps absorb the majority, with composting, digestion, and incineration handling smaller portions depending on local infrastructure.
Why the Destination Matters
The environmental impact of wasted food depends almost entirely on where it ends up. Food donated to people offsets the resources needed to produce new meals. Food converted to animal feed stays in the food system. Composting returns nutrients to the soil without producing methane. Anaerobic digestion captures energy while also producing fertilizer. Landfilling does none of these things and actively generates greenhouse gases for years.
This hierarchy is why cities and states are increasingly passing laws that ban or limit food waste in landfills, requiring large generators like grocery stores, restaurants, and institutions to compost or digest their organic waste instead. Vermont, California, Massachusetts, and several other states now have some form of organic waste diversion mandate in place. For households, the practical version of this shift is the growing availability of curbside food scrap collection, backyard composting programs, and community drop-off sites that keep food out of the trash and route it somewhere more useful.