Composting toilets break down human waste through the composting process, making them handy in homes that lack a traditional plumbing system.
We researched dozens of composting toilets, considering their design, durability, sturdiness, odor removal, and ease of installation and use. Our best overall pick is the Nature's Head Composting Toilet with Spider Handle, thanks to its space-saving design and effective odor management.
Here are the best composting toilets.
Best Overall: Nature's Head Composting Toilet with Spider Handle
Who else recommends it? BestReviews and Bob Vila also picked the Nature's Head Composting Toilet.
What do buyers say? 89% of 600+ Amazon reviewers rated this product 4 stars or above.
There’s no shortage of advocates for the Nature’s Head Composting Toilet with Spider Handle. This composting toilet is easy to install and simple to use. It has made a name for itself with its low maintenance needs and an odor-free operation.
While originally intended for marine applications, this composting toilet from Nature’s Head is frequently installed in RVs, cabins, outhouses, tiny houses, and more. This version equipped with a spider handle is frequently chosen for its space-saving design, though a more conventional crank handle model is available also. It boasts a considerable capacity for solids—60 to 80 uses, while also easily handling toilet paper. The liquids container will need to be emptied daily or every other day, according to users.
For some, the Nature’s Head Composting Toilet is their first introduction to composting waste management—and nearly everyone is impressed by how easy it is to utilize this commode. A number of people said they were apprehensive at first but have been pleased with all aspects of this composting toilet, including how effective it is at odor management. It’s wired for 12V power to keep the exhaust fan operational.
Some people experienced minor troubles with the exhaust fan or found it necessary to upgrade the unit to a more powerful fan. The only other frequent modification is to add finer mesh screen to the external vent to keep out tiny nuisance insects, such as no-see-ums.
Best for Odor: Sun-Mar Excel Self-Contained Composting Toilet
Odor management is a top concern when shopping for a composting toilet, and the Sun-Mar Excel Self-Contained Composting Toilet addresses this issue with unique features aimed at eliminating smells.
The Excel model from Sun-Mar sets itself apart from other composting toilets with a thermostatically controlled heater that aims to evaporate liquids quickly, thereby reducing odors. A rear fan also assists in evaporation and odor management by channeling a flow of air over the evaporating chamber before expelling it out a vent stack. It should also be noted that this composting toilet boasts NSF Standard 41 certification for its composting ability.
Users find the function of this composting toilet to be as promised, with many positively noting the lack of odors when using this model. However, a few people found the step to be precarious and suggest replacing it with a wider, more stable option.
Best High Capacity, Non-Electric: Sun-Mar CENTREX 3000 NE (Non-Electric)
A central composting system is the best solution if you’re in need of a high capacity composting toilet since it features a considerably larger composting system. The Centrex 3000 is a non-electric option that can be installed in off-grid applications where a power supply is lacking.
The unit comes fully assembled, and just requires a connection to a gravity flush toilet of your choice that uses one pint (or less) per flush. Unlike many models of composting toilets with self-contained composters, the Centrex 3000 is equipped to handle 5 adults for residential use or up to 8 adults for seasonal use. How frequently you need to empty the unit will depend on use, but the manufacturer states that central composting systems only require emptying every few months for full-time use and once or twice a year for seasonal use.
For individuals that don’t want the hassle of frequently emptying a self-contained composting toilet, a central composting toilet system is a worthwhile investment.
Best High Capacity, Electric: Sun-Mar Centrex 3000 Electric Composting Toilet System
If you have space for a central composting toilet system and a power supply, consider the Centrex 3000 for a high-capacity composting toilet. This model can handle the needs of up to 6 adults for residential use or 9 adults with seasonal use.
Unlike other models of high capacity central composting systems, the Centrex 3000 features an autoflow design that moves composted material along into a collection chamber. This eliminates the typical ‘drawer’ design that must be emptied on other composting toilet systems. Instead, the collection chamber makes it easy to dispose of finished compost.
People that have installed this high capacity composting system and paired it with a compatible dry toilet are typically very satisfied with the unit’s performance and report low to no odors.
Best Compact: Sun-Mar Spacesaver Electric Waterless Self-Contained Composting Toilet
If you’re short on space, consider a compact composting toilet. The Sun-Mar Spacesaver Composting Toilet requires less room for installation while still providing eco-friendly waste management.
The Sun-Mar Spacesaver model measures just 19.5 inches wide and 23 inches deep, requiring total depth clearance of 38 inches. Other models of composting toilets require up to 46 inches of clearance for installation. This compact composting toilet is an especially good option for boats, tiny houses with limited bathroom space, or small RVs. It costs considerably more than conventional composting toilets, but if space is at a premium, then it may be worth it to consider this space-saving model.
A smaller commode also means a smaller composting bin, so expect to empty this unit more often. For seasonal use, it’s rated for 3 adults, but if you plan to use it full-time in a residential capacity, it’s more suited for 1 adult. People that have installed this compact composting toilet mention that the seat is higher than expected, and it may be necessary to replace the somewhat small step that is included with the toilet.
Best Portable: Sun-Mar GTG Portable Electric Waterless Toilet
If you’re looking for a portable composting toilet that can turn just about any space into a private privy, check out the Sun-Mar GTG Portable Electric Toilet.
This composting toilet is a newcomer to the market, but Sun-Mar is one of the leading manufacturers of composting toilets. The GTG model simply plugs into a 110V outlet (adaptor for 240V outlets included) and features a divider for liquid and solid wastes. Optional mounting brackets are included if you want to make the GTG a more permanent fixture.
Since this composting toilet is designed to go anywhere, it forgoes the standard composting chamber on more permanent fixtures. Instead, a solids bin that must be lined with composting liners is used to collect waste and will need to be regularly emptied. This model is a step up from camping toilets, however, thanks to the exhaust fan and vent to keep odors under control.
Best Budget: Stansport Portable Toilet
For a budget composting toilet, consider using a portable camping toilet lined with disposable composting bags. The Stansport Portable Toilet is a sturdier and more comfortable option when compared to many DIY composting toilets using 5-gallon buckets.
If you don’t mind using biodegradable liner bags and making more frequent trips to empty the commode, then using the Stansport Portable Toilet as a budget composting toilet is a great alternative to spending $900 or more for a conventional composting toilet. The Stansport will support up to 350 pounds of weight, and while some people were skeptical at its relatively small size, most reviewers said they were impressed with its capacity.
For a composting toilet at a fraction of the cost, try the Stansport Portable Toilet for your next camping trip, boondocking RV trip, or during long weekends at your off-grid cabin. While its small size and dependence on biodegradable bags might not make it an ideal full-time composting toilet, it’s a great alternative for short-term use or occasional needs.
What to Look for in a Composting Toilet
When deciding on a composting toilet for your home or cottage, you will need to consider whether it's better to have a self-contained system or a split system.
- Self-contained system composting toilets are the easier option to install and they are also the more affordable choice. These toilets can be portable or fixed, but the entire composting process is contained inside the toilet. They will typically have a detachable tank, a liquid drain to remove waste, and some toilets will also have a water supply line or water storage tank to help flush waste.
- Split system composting toilets are more like standard home toilets because both systems carry the waste from the toilet to a different location. While a typical toilet will flush waste to a septic tank or to a municipal waste system, a split system composting toilet flushes waste to a central bio-drum, hopper, or storage tank for composting. Systems equipped with a hopper can greatly improve the composting process, making them a good choice for eco-conscious homes.
Composting toilets tend to be bigger than a standard toilet, so you need to make sure that you have enough space in the bathroom to install and comfortably use the toilet. If you have a small condo, house, or mini-home, then you will either need to stick with a standard option or look for a compact composting toilet that can fit inside the limited space.
Composting toilet manufacturers will typically include the tank capacity in the product information, so you can make an informed decision about the best toilet for your home. Tank capacity refers to the amount of waste a composting toilet tank can hold, and it is measured by the number of people. This means that if you have a family of four, then you need to look for a composting toilet that is rated for four or more people.
It's also important to note whether the measurement is based on seasonal use or residential use. A toilet rated for seasonal use by four people will not have the capacity to handle residential use by four people. In this case, it's better to look for a different toilet with a larger tank capacity because if the tank fills before the waste can break down you no longer have usable fertilizer for the lawn, you just have human waste that needs to be disposed of properly according to local laws.
Electricity and water requirements
Many composting toilets can work without needing to be connected to a source of electricity or water. These models can range from portable options that are excellent for camping to large, stationary toilets. However, not all composting toilets operate without electricity or water. Some toilets connect to a 110V electrical system to provide power to a fan. The fan helps increase the flow of oxygen to the aerobic bacteria. There are also composting toilets that connect to a water line or come with a water storage tank that can be used to help flush waste.
One factor that is often overlooked is that a composting toilet needs to be properly vented to avoid the build-up of odors and gases created by the composting process. Improper ventilation will also slow the composting process because the bacteria are aerobic, meaning that they need oxygen to function. While some composting toilets have a fan that helps move oxygen into the tank and force stagnant air out, you may also need to add organic materials, like sawdust, onto the waste to help block the odor without negatively impacting the bacteria.
How does a composting toilet work?
Composting toilets are designed to hold waste in a tank where aerobic bacteria can break down the waste products and create usable fertilizer. They function similarly to a septic system in that they separate the solid and liquid waste to help facilitate the composting process. Keep in mind that the waste will need to be emptied regularly because it does not flow into a septic system or municipal waste system.
What is a composting toilet?
A composting toilet is a type of toilet that collects and breaks down human waste and creates fertilizer as a byproduct. These toilets may have a water line to help flush liquids and solids waste, but in many cases they are dry toilets that take care of waste with bacteria. Users need to manually empty the toilet about once every 3 weeks to 2 months, depending on the frequency of use and the toilet tank capacity.
How do you empty a composting toilet?
Continuous cycle composting toilets will usually have a tray located at the bottom of the toilet that can be pulled out for easy emptying. Smaller composting toilets may use bio bags that can be lifted out of the toilet when they need to be replaced. Similarly, container composting toilets have a waste container that can be lifted out of the toilet for emptying.
How often do you empty a composting toilet?
The frequency with which a composting toilet needs to be emptied depends primarily on how often you are using the toilet, but the tank capacity is also a factor. On average, you will need to empty a composting toilet about once every 3 weeks to 2 months, depending on the number of people using the toilet.
Why Trust The Spruce
Erica Puisis is a writer specializing in interior design and plant care. She writes about home products for The Spruce and has also contributed to Forbes and leading smart home blogs like Smart Home Solver and TechDigg. Additional reporting was done by Timothy Dale, an expert writer specializing in the home renovation, repair, and construction niche.