10 Things You're Throwing in the Trash That You Could Be Composting

Here's a number worth sitting with: food scraps and yard trimmings together make up about one third of everything American households throw away [U.S. EPA]. Most of that gets buried in a landfill, where it breaks down without oxygen and releases methane — a greenhouse gas far more potent than carbon dioxide in the short term [U.S. EPA]. The frustrating part? A huge share of that "trash" was never really trash at all. It was compost material headed to the wrong bin.

Everyone knows vegetable peels can be composted. But the list of things you can keep out of the garbage goes much further than carrot tops — and a few of the items below surprise almost everyone. Here are ten things you're probably throwing away right now that could be feeding your soil instead.

1. Coffee Grounds — and the Paper Filter Too

Used coffee grounds are one of the best free compost ingredients there is. Despite their brown color, grounds count as a "green" (nitrogen-rich) material, with a carbon-to-nitrogen ratio of roughly 20:1 — right in the sweet spot microbes love [Oregon State University Extension]. Worms seem to like them too.

And don't separate the filter: standard paper coffee filters are compostable right along with the grounds. If you brew a pot every morning, that's a daily handful of premium compost feedstock going straight into your trash. For the full breakdown on which filters work, see our guide to whether coffee filters are compostable.

2. Eggshells

Eggshells are almost pure calcium carbonate, a mineral that helps buffer compost pH and feeds your soil calcium — the same nutrient that prevents blossom-end rot in tomatoes. They break down slowly if tossed in whole, so crush them first; the smaller the pieces, the faster they disappear.

Rinsing isn't strictly required, but a quick crush-and-toss habit turns every breakfast into a soil amendment. We covered the details — including the raw-egg safety question — in our complete guide to composting eggshells.

3. Paper Towels and Napkins

If a paper towel was used to wipe up water, food spills, or vegetable scraps, it's compostable — it's just carbon, the "brown" material every compost system needs to balance wet food scraps. The same goes for napkins and even the cardboard tube in the middle of the roll.

The exception: paper towels soaked in cleaning chemicals, bleach, or large amounts of grease should still go in the trash. But the everyday kitchen wipe-up? That's brown material you're paying to send to a landfill.

4. Tea Bags (With One Caveat)

Loose tea leaves are a straightforward green material. Tea bags are too — if the bag itself is paper. Some premium "silky" pyramid bags are actually woven from plastic mesh (nylon or PET) that will never break down and can shed microplastics into your compost.

The quick test: paper bags feel like paper and tear easily. If the bag is silky, shiny, or stretchy, rip it open, compost the leaves, and trash the bag.

5. Stale Bread, Rice, and Pasta

Bread, cooked rice, plain pasta, crackers, cereal — starchy leftovers are all biodegradable and rich in carbohydrates that microbes tear through quickly. Most people trash them for one understandable reason: in an open backyard pile, starches can attract rodents and flies before they break down.

The fix is containment. Bury starches deep in the center of a hot pile, or skip the problem entirely with a sealed electric composter, where pests can't smell or reach anything. Either way, stale carbs are microbe food, not garbage.

6. Greasy Pizza Boxes

Clean cardboard is recyclable — but the moment cheese grease soaks in, most recycling programs reject it. That's why pizza boxes are one of the most-trashed packaging items in America. Here's the twist: grease-stained cardboard is fine for composting. The oil that ruins recycling is just another food residue to compost microbes, and the cardboard itself is excellent brown material.

Tear the box into palm-sized pieces so it breaks down faster, and compost the greasy half while recycling the clean lid. One box, zero landfill.

7. Nut Shells

Peanut shells, pistachio shells, walnut and pecan shells — all compostable carbon. They're dense, so they decompose slowly; crush them underfoot or with a rolling pin first. One genuine exception worth knowing: black walnut shells and hulls contain juglone, a natural compound that inhibits the growth of tomatoes, peppers, and several other garden plants, so keep those out of compost destined for a vegetable bed [Purdue University Extension].

8. Hair and Pet Fur

Strange but true: hair is one of the most nitrogen-dense materials you can compost. Clean out your hairbrush, empty the dog brush after grooming, and toss it all in. Hair mats easily, so sprinkle it in thin layers rather than dropping in a clump. It decomposes slowly — but it decomposes, which is more than you can say for it sitting in a trash bag.

9. Toothpicks, Wooden Skewers, and Chopsticks

Plain, untreated wood is compost material, full stop. Toothpicks, bamboo skewers from last night's kebabs, disposable chopsticks, wine corks (real cork, not plastic), and even wooden ice cream spoons all qualify. Snap the bigger pieces so they break down faster. Skip anything painted, lacquered, or glued.

10. Meat, Dairy, and Cooked Leftovers — With the Right System

This is the big one. Every traditional composting guide tells you to keep meat, fish, cheese, and oily cooked food out of the pile — and for an open backyard bin, that's correct advice. Those foods rot before they compost, and the smell draws every raccoon, rat, and fly in the neighborhood. Our list of what you can't compost covers the standard rules.

But "don't put it in an open pile" is not the same as "can't be composted." In a sealed electric composter like the Reencle Prime, a heated, aerated chamber and a living microbial culture break down meat, dairy, and cooked leftovers that a backyard pile can't safely handle — and turn them into real compost, not just dried food scraps. We explain the microbiology in why Reencle can compost meat and dairy.

For most households, meat and cooked food are the single biggest category of food waste still going to the landfill. Solving that one category changes your trash output more than everything else on this list combined.

Quick Reference: What Goes Where

Why This List Matters More Than It Seems

When food and paper break down in a landfill, they're compacted under tons of other waste with no oxygen. Anaerobic decomposition produces methane, and municipal landfills are one of the largest human-caused methane sources in the United States [U.S. EPA]. The same banana peel composted at home becomes stable organic matter that feeds soil instead.

You don't have to overhaul your life to make a dent. Start with the two or three items on this list you throw away most — for most people that's coffee grounds, paper towels, and cooked leftovers — and redirect just those. If you want to go further, our guide to reducing food waste at home covers fifteen more practical steps.

Frequently Asked Questions

What percentage of household trash is compostable? Food scraps and yard trimmings make up roughly one third of U.S. household waste by weight, according to the EPA. Add compostable paper products like napkins, towels, and greasy cardboard, and well over a third of a typical trash bag could be composted instead.

Can you compost paper towels and napkins? Yes, as long as they were used on food, water, or plain messes. They count as carbon-rich "brown" material. Skip towels soaked in cleaning chemicals, bleach, or heavy grease.

Why can't meat and dairy go in a regular compost pile? In an open pile, meat and dairy rot faster than they compost, producing strong odors that attract rodents, raccoons, and flies. A sealed electric composter avoids the problem because the chamber is enclosed, heated, and aerated — nothing can smell it or reach it while microbes break it down.

Are pizza boxes compostable or recyclable? Both — in parts. The grease-soaked sections can't be recycled but compost just fine. The clean parts (usually the lid) can go in the recycling bin. Tear the greasy cardboard into small pieces so it breaks down faster.

Do eggshells need to be washed before composting? No. A quick rinse reduces any odor risk, but it isn't required. The more useful step is crushing them — whole shells can take a year or more to disappear, while crushed shell fragments break down much faster.

The Bottom Line

The trash can is a habit, not a verdict. Coffee grounds, eggshells, paper towels, tea bags, stale bread, greasy pizza boxes, nut shells, hair, plain wood — and yes, even meat and dairy with the right system — all have somewhere better to go. Pick the three items you toss most often, give them a new destination, and your actual garbage output will shrink noticeably within a week. The soil wins, the landfill loses, and nothing about your routine gets harder.

References

1. U.S. Environmental Protection Agency. Composting at Home. https://www.epa.gov/recycle/composting-home
2. U.S. Environmental Protection Agency. Basic Information about Landfill Gas. https://www.epa.gov/lmop/basic-information-about-landfill-gas
3. Oregon State University Extension Service. Coffee grounds perk up compost pile with nitrogen. https://extension.oregonstate.edu/news/coffee-grounds-perk-compost-pile-nitrogen
4. Purdue University Extension. Black Walnut Toxicity. https://www.extension.purdue.edu/extmedia/HO/HO-193.pdf
5. Cornell Waste Management Institute, Cornell University. Compost Chemistry. https://compost.css.cornell.edu/chemistry.html