For folks with mobile homes or tiny houses that lack the plumbing to support a traditional flushing commode, a composting toilet could be the solution. This unusual kind of toilet uses aerobic bacteria to break down human waste and stows it in a neat, easy-to-remove package.
This type of toilet separates liquids from solids, breaking down the solid waste and toilet paper with organic materials and bacteria to become manure. While these folks can dispose of the waste in a trash bag if local regulations allow, it can also be used in a garden—if they should choose. This guide offers shopping tips and evaluates the best composting toilet picks below.
- BEST OVERALL: Nature’s Head Self-Contained Composting Toilet
- RUNNER-UP: Sun-Mar Excel Electric Waterless Composting Toilet
- BEST BANG FOR THE BUCK: Sun-Mar GTG Electric Composting Toilet
- BEST FOR ODOR CONTROL: OGO Compost Toilet
- BEST PORTABLE: Boxio Portable Composting Camping Toilet
- BEST COMPACT: Separett Villa 9215 AC/DC Composting Toilet
- BEST HIGH-CAPACITY: Sun-Mar Centrex 3000 High-Capacity Composting Toilet
- ALSO CONSIDER: Saniflo SaniPLUS Macerating Upflush Toilet Kit
How We Chose the Best Composting Toilets
We considered a variety of factors when making our selections of top composting toilets. Since capacity is crucial, we only chose composting toilets that could capably handle multiple adults or entire families. Odor control is absolutely vital for a composting toilet to be effective, so we selected models with well-designed ventilation systems that prevent odors from overtaking the area around the toilet.
And, since a composting toilet for RV, tiny home, or boat use should be able to fit in a small space, we chose compact models while still keeping in mind that the toilet’s seat should be large enough to accommodate an adult comfortably. While cost was not a major factor, we did favor composting toilets that offer the best bang for the buck.
Our Top Picks
The following are some of the best composting toilets (or alternatives to composting toilets) on the market. Be sure to review each and then check out the top shopping considerations listed below.
Photo: Amazon.com
When it comes to a durable, easy-to-use composting toilet, it’s tough to beat this Nature’s Head model. It diverts urine into an easily removed tank and features a side-mounted “spider” handle for churning the solid waste inside the tank. The waste tank is large enough for two adults to use full-time, which will require emptying every 4 to 6 weeks.
The Nature’s Head composting toilet uses an electric fan to draw fresh air in and push odors out, helping to keep smells at bay. While the fan uses 12-volt power, it can convert to 110 volts with a kit purchased directly from Nature’s Head.
Product Specs
- Weight: 28 pounds
- Capacity: 2 adults
- Power: 12 volts
Pros
- Large waste tank is enough to handle 2 adults’ worth of regular bathroom trips
- Lightweight and portable allows users to bring this model on a road trip, camper, or anywhere else it may be needed
- Ventilation fan eliminates odors by pulling the gasses away from the room and pushing them outside
- Spider-handle design allows users to churn the waste for better breakdown
Cons
- Converting to 110 volts requires contacting Nature’s Head for a conversion kit
Get the Nature’s Head composting toilet at Amazon.
Photo: homedepot.com
The Sun-Mar Excel composting toilet is worth looking into when shopping for an eco-friendly model. This composting toilet uses an electric fan to dry liquids, but it also draws air into the tank and pushes waste gasses out of the vent to purge odors. The self-contained tank is large enough for three adults.
Even with the Sun-Mar Excel’s large capacity, it weighs just 60 pounds, and installation should be fairly easy. It may, however, require an additional electric kit to wire it for 12-volt power in a boat or camper.
Product Specs
- Weight: 60 pounds
- Capacity: 3 adults
- Power: 12 volts
Pros
- Large capacity can handle up to 3 adults’ worth of regular bathroom trips without filling too quickly
- Includes pull-down step to save space but also make it easier to sit safely
- Vent and fan remove odors and push them outside to prevent them from permeating into the space
Cons
- It’s heavier than most composting toilets, so folks may require help when moving or installing it
Get the Sun-Mar Excel composting toilet at The Home Depot.
Photo: homedepot.com
The Sun-Mar GTG composting toilet is worth a look when searching for a compact, portable design that also composts. Unlike other travel models that still need emptying into a sewer, the self-contained GTG produces the same type of compost as other much larger toilets. And its waterless design allows you to save on your water bill.
The GTG is a waterless toilet with a 12-volt-powered fan. It separates solid and liquid waste, dividing them into two easy-to-remove containers. It weighs just 25 pounds—a plus for portability—and measures 19.8 inches high by 15.75 inches wide 24 inches deep, so it will fit in most bathrooms of tiny homes, RVs, and campers without issue.
Product Specs
- Weight: 25 pounds
- Capacity: N/A
- Power: 12-volt power
Pros
- It’s an affordable option compared to most other composting toilets
- The venting fan manages odors and prevents them from backing up into the space
- Lightweight and portable means a simple installation and repositioning whenever necessary
- Compact design allows it to fit in tight spaces, even stowing away when necessary
Cons
- The seat might be slightly on the small side, making sitting less than completely comfortable
Get the Sun-Mar GTG composting toilet at The Home Depot.
Photo: amazon.com
Folks who love the idea of a composting toilet but not necessarily the odors they can emit should consider OGO’s compost toilet. This sleek machine features a small fan that pulls fumes and excess moisture away from the waste, pushing it outside through a ventilation system. This prevents odors from escaping and permeating the living space. The fan runs on 12-volt power, so it’s suitable for RVs and most tiny homes, though a converter may be necessary for standard voltage.
This unit separates solids from liquids. The liquids end up in the 2.4-gallon bottle in the front of the toilet while the waste heads to the solid bin. This allows for 25 to 30 uses before requiring emptying. The stainless steel power agitator ensures that bacteria and enzymes can access all of the waste for better composting as well. It may be slightly small for some, measuring just under 18.5 inches tall by 16 inches wide by 15 inches deep.
Product Specs
- Weight: 34 pounds
- Capacity: 25 to 30 trips
- Power: 12-volt power
Pros
- An electric fan pulls fumes and moisture away from the waste and pumps it outside for better odor control
- Stainless steel agitator ensures that enzymes and bacteria can access all of the solid waste
- Large-capacity liquid bottle and bin allow for 25 to 30 uses before emptying for convenience
Cons
- The compact design might be too small for some folks to feel comfortable sitting on this composting throne
Get the OGO composting toilet at Amazon, Camping World, or OGO Toilet.
Photo: amazon.com
What it doesn’t have in fancy fans, agitators, and ventilation the Boxio toilet makes up for in portability. Weighing just 8.3 pounds, this plastic milk-crate-size composter can go just about anywhere you need to, well, go. It separates liquid from solids, and this helps prevent odor even without a power source or fan.
The Boxio’s main solid compartment has a capacity of 1.3 gallons and a separate bottle for liquid. This allows for up to 10 toilet trips before requiring emptying. For folks who don’t want to hold onto that nutrient-rich waste, Boxio’s Bio Bags are biodegradable and therefore disposable, making cleanup easy, mess-free, and environmentally friendly. This recycled-plastic throne measures 11 inches high by 11.81 inches wide by 14.75 inches deep. Given its size, however, it might not be the most comfortable composting toilet to sit on.
Product Specs
- Weight: 8.3 pounds
- Capacity: Enough for 10 trips
- Power: None
Pros
- Lightweight design that’s easy to take anywhere you might need it
- Separates liquids and solids to prevent odors from building and escaping
- Despite its very compact size, it can handle 10 toilet trips between the solid bin and liquid bottle
Cons
- Might not be the most comfortable composter toilet seat for sitting on due to its compact size
Get the Boxio composting toilet at Amazon or Boxio.
Photo: amazon.com
For an all-around compact composting toilet, check out the Separett Villa 9215. This waterless self-contained composting toilet has an electric fan to exchange gases, operating on both 110 volts in a house or on a 12-volt system in a boat or motor home. It’s lightweight at 30 pounds and on the small side, so it’s quite portable.
The kit provides the toilet, adapters for both 110-volt and 12-volt power, and all the parts for direct venting and for tying the liquid drain into a gray water system. The tank is large enough for around 3 weeks of use by an average-size family. If there’s a downside, it’s that the venting system was originally designed for European plumbing. Although it’s been revamped for the U.S. market, there are several adapters to use to mate it with 3-inch schedule 40 pipe.
Product Specs
- Weight: 30 pounds
- Capacity: Family of 4
- Power: 12 or 110 volts
Pros
- Compact and lightweight makes moving it about (even taking it on the road) a breeze
- Multiple power options, with 12-volt and 110-volt adapters provided with the kit
- Ample tank capacity can handle a family of 4’s bathroom trips
- A fan ventilates odors to prevent them from escaping the toilet and backing up into the room
Cons
- There are multiple adapters (which are included) to mate the vent with a 3-inch schedule 40 pipe
Get the Separett composting toilet at Amazon.
Photo: homedepot.com
A composting toilet that sees regular use must be able to handle a lot of waste, and this high-capacity compost toilet system from Sun-Mar does. This model, which works with a 1-pint flush toilet or waterless toilet (sold separately), is capable of handling five adults or a family of seven for daily residential use or up to eight adults for seasonal use.
Once the waste is flushed from the toilet, it travels through a drain pipe to the Centrex 3000, which uses a biodrum to turn the human waste into fertilizer that can be recycled into the soil. Since the Centrex 3000 requires no electricity, it’s ideal for use as an off-grid living composting toilet or in tiny houses with no consistent electrical connection. Just keep in mind that at 30.25 inches high by 71 inches wide by 27.5 inches deep and 110 pounds, this composting toilet system does take up a fair amount of space.
Product Specs
- Weight: 110 pounds
- Capacity: 5 to 7 adults
- Power: Nonelectric
Pros
- High capacity can handle regular bathroom trips for up to 7 adults
- No electricity require, which makes it ideal for off-grid cabins and camps
- Biodrum breaks down waste to turn it into fertilizer, which you can spread into soil or add to a compost pile or compost bin
Cons
- It’s likely too large to use as a composting solution in an RV
Get the Sun-Mar Centrex composting toilet at The Home Depot.
Photo: amazon.com
Many folks who plan to install a toilet below their sewer line think that composters are the only option, but that’s not the case. With a macerating upflush toilet kit like this model from Saniflo, DIYers and pros can install a toilet up to 15 feet below their sewer line. The whole kit takes up roughly the same amount of space as a standard toilet, and it requires a 110-volt power source and water supply.
This kit features a relatively standard-looking toilet and a macerating tank and pump. The stainless steel macerating blades break the waste down into a slurry while the 10-pounds-per-square-inch (psi) pump pushes that slurry out of the tank and into the sewer system. This tank can also handle the wastewater from a sink and shower, allowing for a complete bathroom installation below the sewer lines. However, folks looking for a traditional composting toilet will have to look elsewhere as this kit is designed to get rid of the waste, not allow it to break down into nutrient-rich soil.
Product Specs
- Weight: NA
- Capacity: Unlimited
- Power: 110 volts
Pros
- Install a fully functioning flushing toilet up to 15 feet below the sewer lines
- Macerating blades and a 10-psi pump work together to remove the slurry, preventing users from emptying bins or bottles
- Can also handle wastewater from 1 sink and 1 shower, allowing for complete bathrooms
Cons
- It does not hold on to waste to allow it to break down into compost
Get the Saniflo composting toilet at Amazon.
What to Consider When Choosing a Composting Toilet
Keep the following considerations in mind to make the best choice of composting toilet for any given application.
Types of Composting Toilets
Before purchasing a composting toilet, be sure that it will work in a given location. There are two types—self-contained and split/central systems—and while they both break down waste, they work a bit differently and have different requirements.
Self-Contained System
A self-contained compost toilet system consists of a small toilet with a detachable tank and a liquid drain for removing waste. Some self-contained systems are portable, which works for camping trips or boat rides and can be set up in a space where plumbing won’t reach, like a workshop or garage.
The entire composting process occurs within the toilet, hence the name. When full, remove the tank and empty the manure. These systems sometimes have freshwater tanks or supply lines as well to flush waste into the chamber below.
Split System or Central System
Composting toilets that work with split or central systems are similar to a traditional toilet. They connect to a system of pipes that take the waste to a central biodrum, hopper, or tank, which is where composting takes place. The hopper churns the waste, allowing it to break down while also venting the odorless gasses. When the tank fills, empty it just like a self-contained toilet.
A split compost toilet system is much more expensive than self-contained composters, as they require a hopper, usually installed below the toilet. The hoppers are a benefit because they significantly increase the amount of compost they can hold. They can be an attractive solution for permanent off-grid or eco-conscious homes, but the setup makes these composting toilets a poor choice for portability.
Available Space
Composting toilets take up a bit more floor space than a traditional toilet, and they don’t have an additional holding tank to contend with. For a tiny home or boat, look for a compact composting toilet with a smaller waste tank.
If space for a split system is available, it might be worth the investment to get the increased holding capacity. Areas like garages and cabins sometimes have the flexibility for adding a hopper. In warmer climates, installing the tank outside is an option.
Portable vs. Composting
A portable toilet and a composting one may seem similar, but there are some very significant differences. Composting toilets use bacteria to break down human waste. They separate solid and liquid waste, allowing the bacteria to feed upon the organic compounds in each. After the composting process, the humanure can fortify a lawn or garden. The byproduct of the composting process fertilizes the soil and brings nutrients to plants.
A portable toilet does nothing of the sort. With portable toilets, everything goes into one waste tank where liquids are not separated from solids. Even after pouring enzymes and deodorizers down into the tank to break solids down and offset odor, the end product still needs to find its way into a sewer or septic system. So while a portable toilet can be handy for camping and boating trips, it may not be the best choice for permanent residences like mobile homes and tiny abodes.
Tank Capacity
When searching for the best composting toilet, the number of people who will be using it should determine how big of a tank is required. Manufacturers often break this down by family size and appropriate use.
For instance, a split system with a high-capacity tank might handle waste from three adults or a family of five, while a self-contained composting toilet with a 5-gallon tank would be more than enough for one adult. The idea here is that by sizing the tank correctly, waste will have enough time to break down into manure before the tank fills.
Utility Usage
Some composting toilets use electricity to power a fan that draws air into the tank and across the waste. The air is rich in oxygen to feed the aerobic bacteria breaking down the waste. This also exchanges the carbon dioxide created by the bacteria, venting it into the air. Many work with a home’s 110-volt system, while some work with both 110-volt AC and 12-volt DC from a car or RV battery.
A composting toilet may also need a water line. While this seems counterintuitive, the composting toilets that use water consume very little with each flush—far less than a standard residential toilet. Waterless and nonelectric models are available too, so consider the utility setup and household budget when choosing a toilet that will work best.
Odor Removal
The gases created by a composting toilet’s bacteria need to be vented. Otherwise, odors could build up, or the bacteria’s performance could suffer from a lack of fresh oxygen. The fan some models use to draw air into the tank also forces the gases out through the vent, banishing unpleasant smells. Adding organic materials like sawdust on top of the waste after each use can block the odor while still allowing the bacteria to break down the solids.
FAQs
Still not feeling flush with knowledge about these toilets? Here are the answers to some important frequently asked questions. If you need more info, contact your toilet’s manufacturer.
Q. How do composting toilets work?
Composting toilets hold waste in a tank and allow aerobic bacteria to break it down to a material similar to rich, moist soil.
Q. How do you install a composting toilet?
Installing a self-contained nonelectric waterless unit is straightforward. The only concern is venting it outside. The directions that come with the toilet will have suggestions for vent-pipe sizes and heights.
Q. Do you put toilet paper in a composting toilet?
Moderate amounts of toilet paper should be fine. Single-ply is probably best, but most composting toilets won’t have an issue since toilet paper is biodegradable.
Q. Can you use a composting toilet as a real toilet?
Yes. The manure you end up with after the composting process is feces—just broken-down feces.
Q. How long does a composting toilet take to work?
This depends on how often you’re supplying the toilet with fresh waste. The bacteria in your composting toilet will begin breaking down waste immediately, and it should take a few weeks to fill with humanure.
Q. Where should I empty a composting toilet?
If you don’t want to use your compost for your lawn and garden, check with your local code enforcement about disposal. Some jurisdictions allow you to bag it up and throw it in your garbage.
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