A compost toilet is a waterless toilet that breaks down human waste into usable compost

A compost toilet separates urine and solid waste, then uses natural decomposition to turn the solids into soil-like material over time. Unlike a septic system, it needs no plumbing connection and produces no sewage. The finished compost can be used on ornamental plants and trees, though most people do not use it on vegetable gardens due to safety concerns.

The simplest version is a bucket toilet: a five-gallon bucket with a toilet seat on top, filled with sawdust or wood chips after each use. More permanent versions use a wooden box or commercial composting chamber buried in the ground or sitting above it. All versions work the same way — solid waste mixes with carbon material (sawdust, leaves, straw), bacteria and fungi break it down, and the pile heats up as it decomposes.

Key Takeaways

  • A bucket toilet costs $50 to $200 to build and requires only a five-gallon bucket, toilet seat, and sawdust or wood chips.
  • Urine should be diverted into a separate container to speed decomposition and reduce odor in the solid waste.
  • The compost pile needs carbon material added after each use and should be turned or left to sit for 6 to 12 months before the finished material is safe to use.
  • Compost toilets work best in dry climates and produce no smell if maintained correctly, but they require discipline about adding carbon material every time.

Building a Basic Bucket Toilet

Start with a five-gallon food-grade bucket (available at bakeries, restaurants, or online for $5 to $15). Drill a hole in the lid large enough to fit a standard toilet seat, or cut the lid out entirely and attach a wooden frame around the bucket rim. Screw a toilet seat onto the frame or directly to the bucket. Line the inside bottom with four to six inches of sawdust, wood chips, or shredded leaves.

After each use, add a handful of sawdust or wood chips on top of the waste. The carbon material absorbs moisture and provides food for the microorganisms that break down the waste. Without it, the bucket becomes wet and smells. Keep a covered container of sawdust next to the toilet so it is always within reach. When the bucket is three-quarters full, empty it into a compost bin or pile outside.

Separating Urine for Faster Composting

Urine contains nitrogen and speeds decomposition, but it also adds moisture and can cause odor. A urine-diverting toilet seat has a front section that channels urine into a separate container and a back section for solid waste. These seats cost $100 to $300 and fit standard five-gallon buckets or wooden boxes.

Collect urine in a sealed container with a tight-fitting lid. It can be diluted with water and used as a nitrogen-rich fertilizer for ornamental plants and trees — typically one part urine to eight parts water. Store it in a cool place or outdoors; it will not smell if kept sealed. Solid waste goes into the bucket with sawdust as usual, and without the added moisture from urine, it dries out faster and produces less odor.

Building a Permanent Wooden Box Toilet

For a toilet that stays in one place, build a wooden box from untreated lumber (pressure-treated wood can leach chemicals into the soil). A typical box is 24 inches wide, 24 inches deep, and 18 inches tall. Drill drainage holes in the bottom, line the inside with landscape fabric to keep sawdust from falling through, and place it over a compost bin or directly on the ground.

Attach a toilet seat to the top of the box. Add a hinged lid or removable cover to keep out rain and insects. Place a bucket or container underneath to catch any liquid that drains through, or dig a shallow pit beneath the box and line it with gravel to allow drainage into the soil. The box itself becomes part of the composting system — as waste accumulates, you can remove the box and move it to a new location, leaving the compost to finish breaking down in place.

Managing the Compost Pile

Every time you empty the bucket or box, dump the contents into a dedicated compost bin or pile at least 10 feet away from your house and any water source. Continue adding carbon material — sawdust, leaves, straw, or shredded paper — in a ratio of roughly three parts carbon to one part waste by volume. The pile should feel damp but not wet, like a wrung-out sponge.

Turn the pile every two to four weeks with a shovel or pitchfork to speed decomposition and reduce odor. If you do not turn it, the pile will still break down but will take longer — typically 6 to 12 months. The center of the pile will heat up as microorganisms work; temperatures above 130 degrees Fahrenheit kill most pathogens. Once the pile is dark brown, crumbly, and smells like soil, it is finished compost and can be used around trees and ornamental plants.

Choosing the Right Location

Place your compost toilet in a spot that is convenient to reach but at least 10 feet from your house, well, or any surface water. It should be on level ground with good drainage — avoid low spots where water pools. If you live in a wet climate, build the toilet on a slight mound or in a raised bed to keep it from sitting in standing water.

Compost toilets work best in dry climates with low humidity. In very wet areas, the pile stays too moist and smells. If you live somewhere rainy, cover the compost pile with a roof or tarp to shed water, and add extra carbon material to absorb moisture. Make sure the location is private and screened from neighbors' view, and check your local health department rules — some areas restrict compost toilets or require permits.

Maintenance and Odor Control

The most common mistake is not adding enough carbon material. If the toilet smells, add more sawdust or wood chips when ready. A well-maintained compost toilet produces almost no odor — what you smell is usually wet waste that has not been covered. Keep the lid closed between uses, and never leave the toilet uncovered.

Check the compost pile monthly. If it looks wet and packed, turn it and add dry carbon material. If it looks dry, add water or urine. Insects like flies and beetles are normal in a compost pile, but if you see maggots in the toilet bucket itself, add more sawdust and cover the bucket tightly. Rodents are attracted to compost piles; use a bin with a tight-fitting lid or bury the pile in a wire cage to keep them out.

Frequently Asked Questions

Can I use the finished compost on my vegetable garden?

Most experts recommend against it because human waste can carry pathogens that survive the composting process. The safest use is on ornamental plants, trees, and shrubs. If you do use it on vegetables, explore it only to the soil, not on the leaves, and wait at least one year after the compost is finished before harvesting.

How much does it cost to build a compost toilet?

A bucket toilet costs $50 to $200, depending on whether you buy a urine-diverting seat. A permanent wooden box toilet costs $150 to $400 for materials. A commercial composting toilet unit runs $1,000 to $3,000. After that, the only ongoing cost is sawdust or wood chips, which you may already have on hand.

Will a compost toilet smell bad?

No, if you add carbon material after every use and keep the lid closed. The smell comes from wet waste that has not been covered. If your toilet smells, you are not adding enough sawdust. A properly maintained compost toilet is odorless or smells faintly like soil.

How long does it take for the compost to be ready?

If you turn the pile regularly, finished compost is ready in 6 to 9 months. If you leave it undisturbed, it takes 12 to 24 months. The center of the pile breaks down faster than the edges, so finished compost is usually ready from the bottom of the pile first.

Do I need a permit to install a compost toilet?

Rules vary by location. Some counties allow compost toilets without a permit, while others require one or forbid them entirely. Check with your local health department or building inspector before you build. If you are on a septic system, you may be able to replace it with a compost toilet; if you are on municipal sewer, you usually cannot.