Toilets that plumb into the mains water supply aren’t an option everywhere. Fortunately, there’s an alternative – and it’s one that can help your garden grow at the same time!
Composting toilets allow human waste to be used as nutritious plant food. But with different designs on the market, how do you make the right choice?
We’re here to help. Check out our reviews of the best composting toilets out there. Then take a look at our buying guide to help you decide which is the right option for you.
The Best Composting Toilet Reviews of 2019
1. Nature's Head Self-Contained Composting Toilet (My Top Recommended)
A lot of thought has gone into the composting operation of this toilet from Nature’s Head. If your priority is substance over style, it should be on your shortlist.
There’s no denying this isn’t the world’s most attractive toilet. It’s made of a speckled off-white plastic of the kind you might see in portaloos at music festivals. So if you’re planning to install it alongside a gleaming bath and sink, it has its drawbacks.
Set that aside, though, and this is a toilet with good composting credentials. It stores urine and solid waste separately, with the solids mixed with appropriate composting material.
It’s up to you to decide what composting base you use. We’ve heard that coconut fiber works well. It’s easy to store too. Sawdust is another good option. Add it to the bin inside the toilet and you’re ready to go.
After you’ve used the loo, it’s a simple case of turning the crank handle to mix the solid waste with the compost base. The materials start composting quickly, so don’t take up a lot of room. For one person using it as their main toilet, expect to empty the bin once every four weeks or so.
Urine is collected separately, and you’ll need to empty the bottle more regularly. It holds up to 2.2 gallons. If there’s just one person using the toilet, you’ll need to empty it every two to five days. This is by far the smelliest part of the whole operation.
This is a toilet that uses no water at all. That makes it a good option if you’re somewhere with water shortages or away from a water source.
You’ll need space at one side to remove the urine container and solid waste bin. You’ll also need to move the bowl backward to do that. That means the toilet needs to be mounted a couple of inches away from the back wall.
Nature’s Head says the design is odorless. We wouldn’t go quite that far. There is a smell, although it isn’t pungent. Imagine damp soil and rotting wood and you’ll be in the right ballpark. For a loo that uses no water at all, we think it’s pretty good.
It also comes with a 12-volt fan that’s mounted on one side of the toilet unit. Turn it on and it will recirculate the air in the bathroom, reducing smells further.
The toilet seat is full-sized and comfortable. It is, though, a little higher than the seat of a standard lavatory. It takes a bit of getting used to, and smaller children will need a step to use it.
The latches, handle and other components are made of stainless steel. They’re hygienic, and will resist corrosion. And all you’ll need for cleaning the toilet bowl is water in a spray bottle and a loo brush.
There’s a lot to love about this toilet, but the design isn’t perfect. We’ve found issues with the way the urine is diverted from the solid waste. If you’re a tall gent, a heavy stream can result in urine getting into the solids container.
There’s also no way of knowing when the urine container is full. Err on the side of caution by emptying it out every couple of days. The alternative is overflowing urine – not pleasant.
What We Like
What We Don't Like
2. Sun-Mar Excel Non-Electric Self-Contained Composting Toilet
Another toilet that can be placed anywhere, Sun-Mar’s Excel-NE requires neither water nor electricity. It’s a great option if you hanker after the off-grid lifestyle.
Let’s get the negatives out of the way first: this really isn’t a looker. The Nature’s Head offering is positively stylish in comparison to this toilet. It looks like an over-sized potty with some kind of medical purpose. On the plus side, it is at least pure white.
The seat is fairly high up, but it comes with a matching step to help. The step is on the flimsy side, though. If the toilet will be used by anyone with mobility issues, we’d recommend replacing it. Something with more weight and a non-slip surface will be much safer.
Now onto the good stuff. This is a loo that can handle medium to high capacity. Sun-Mar recommends it for regular use by two to three people. If you’re only going to be using it now and again – perhaps in a cabin used on weekends – it will cope with five to seven users.
There’s a four-inch vent at the back of the loo which acts like the chimney on a wood stove. Smelly air is carried upwards and away from the bathroom. For best results, the vent should be installed straight up, without bends. And it should finish between two and three feet above the peak of the roof.
This one doesn’t come with a fan as standard, but Sun-Mar offers one as an optional extra. It sits inside the vent and makes for a much pleasanter experience – particularly in hot weather. To power it, use either a 12-volt marine battery or – for maximum eco-friendliness – attach it to a solar panel.
It’s fine to use toilet paper, but don’t throw anything else down the loo. You’ll end up with blockages and unusable compost.
The drum for the compost is variable diameter, and there’s a recessed handle to mix together the materials.
This toilet doesn’t divert urine from the mix. That means there’s no urine container to empty, with none of the associated unpleasantness. The rate of evaporation will depend on local conditions though, and the toilet will need to be connected to a drain. That will avoid any issues with overflow.
If you’re concerned that this means you need to be connected to a mains sewer, don’t be. The drain can be very simple. Simply dig a drainage bed 18 inches deep and line it with plastic sheeting. Then fill it with 6 inches of gravel, covered by 12 inches of sand. Finish by planting with grass and shrubs.
Sun-Mar is expert in this kind of thing and offers detailed instructions on their website. Just make sure you check out local regulations to be sure that your arrangements comply.
If you’re planning to put your loo outside, bear in mind that composting needs a bit of heat. If your location gets below 55 degrees Fahrenheit and you’re using the toilet regularly, you’ll need a heat source nearby.
If you’re only using the toilet occasionally, though, don’t worry about the temperature. The toilet will have time to compost the waste without extra heat.
What We Like
What We Don't Like
3. Separett Villa 9215 AC/DC Composting Toilet
If you’re looking for a composting toilet that’s stylish as well as eco-friendly, the Villa 9215 might be for you.
Unlike many other composting loos, this one looks at home in a contemporary bathroom. It’s made of white, high-gloss polypropylene. And if you’re worried that hits its environmental credentials, don’t be. Every part of this toilet can be recycled.
It can also be used either on or off the grid. It comes with a fan that can be powered by either mains electricity, or by a solar panel or batteries. Energy consumption is just 0.06 kilowatts per 24 hours.
There’s no need for water, other than for cleaning. Urine is collected from a drain at the front of the toilet bowl, while solid waste goes into a separate container. The urine is drained away either to a sewer or, if there’s no sewer, to a drain or holding tank.
A vent at the back of the toilet draws air over the solid waste, reducing nasty smells. The fan will support venting up to a distance of 20 feet. If you need longer venting, it’s possible, but you will need mains power for the fan. An AC-only conversion unit is available.
The solid waste container comes with a lid to help reduce smells further. Line the container with compostable bags to make emptying it easy. Ten bags are included in the package to get you started.
For an average family, expect to have to empty the solid waste container once every three weeks or so. It’s very easy and quick to do.
The toilet is solidly built, and comes with a five-year manufacturers’ guarantee. The fan is guaranteed separately, and is covered for three years.
The seat here is a standard height. That makes it a good option if anyone in your household isn’t steady on their feet. And Separett even offers a child’s seat as an accessory, so little ones can use it in safety and comfort.
So is there anything here not to like?
Well, the solid waste bin isn’t huge. Toilet paper will make it fill up more quickly than some other composting loos on the market.
The solid waste container is covered by an automatic door so you won’t have smells drifting up. We have, though, heard of some issues with the door not closing properly over time.
All in all, though, these feel like minor gripes for a composting loo that works effectively and looks good too.
What We Like
What We Don't Like
4. Nature's Head Dry Composting Toilet with Standard Crank Handle
The second composting loo from Nature’s Head to make our list, the main difference with this model is the handle. Instead of a spider design to turn the waste in the container, this one uses a longer crank handle. It means it’s easier to get hold of, but you’ll need a bit more space at the side of the toilet.
Surprisingly, though, we’ve heard some people complain that the longer handle isn’t easy to turn. That’s particularly an issue if you’re using the toilet in low temperatures, when waste will stay solid for longer.
In other respects, the design is exactly the same.
The finish is the same speckled off-white as the version with the spider handle. It’s shaped like a conventional loo, albeit one with a thick and wide base. But it won’t match standard sinks or baths. The seat is high too, so you may find a step makes it more comfortable to use.
Urine and solid waste are collected separately from different parts of the toilet bowl. This requires a certain amount of precision on the part of the user!
Urine flows through drainage holes at the front. From there it passes into a container housed at the base of the loo. It will need emptying every couple of days.
In order to do that, you’ll need to push the top of the toilet backward. That means installing it with a gap of a few inches from the wall behind.
The container has a handle to make transporting it easy and it comes with a cap to avoid spills.
But, as with the other Nature’s Head toilet, there’s unfortunately no way of knowing when it’s getting full. Overflowing containers are pretty horrible to deal with. We’ve heard of some users installing LEDs around the container in a bid to shed some light on the situation.
Solid waste is collected through a chute at the back of the toilet bowl. The bowl is primed with a compost base like coconut coir, sawdust or peat moss. After using the toilet, the user turns the handle to mix the waste with the compost base.
It doesn’t need to be emptied often – once every three to five weeks for a single person using it regularly. When the time comes, though, it can be a bit awkward to do. A full container is heavy, and it needs to be tipped upside down into a compostable bag.
We’ve found the best way is to secure the top of the bag over the rim of the container first. That way you minimize the chance of the compost mixture escaping when you upend the container. Alternatively, tip it into a wheelbarrow to take it to your composting site.
With this loo you’ll get a handy freebie – a copy of “The Humanure Handbook”. This will give you step by step instructions on how to use human waste safely for compost.
We’ve heard excellent reviews of Nature’s Head’s customer services. They apparently respond quickly and knowledgably to any issues. So even if you’re new to using a compostable toilet, you’ll be in safe hands.
What We Like
What We Don't Like
5. Sun-Mar Corp CSAS-01500B Mobile Electric Waterless Self Contained Composting Toilet
If you’re looking for a composting toilet for your mobile home or boat, check out the CSAS-01500B from Sun-Mar.
Using a loo on the road or high seas results in some very specific requirements. The main issue is that the waste needs to remain inside, no matter how bumpy the journey.
You’ll also have a lower roof on a vehicle or boat than on most buildings. So venting needs to be effective over shorter distances. And space inside a recreational vehicle will be at a premium. Any toilet will need to be compact.
Happily, this toilet overcomes all these problems.
There’s a gasket in the finishing drawer to prevent liquid leaking out of the evaporation chamber. The air intake is located higher up than the standard Sun-Mar toilets, with air ducted down to the evaporation chamber.
The drum is held in place by a locker, so it will stay upright on turbulent seas or potholed tracks.
And the footrest with this version folds away to save space when it’s not in use. You can also detach it when you need to get to the finishing drawer for maintenance.
The vent includes a 12-volt fan to keep the air circulating. This is designed to run continuously while the toilet is being used.
And if you’re on a boat and unable to vent above deck level, the fan includes an activated carbon filter. This get rids of any unpleasant odors, so walking on deck remains a pleasant experience.
Evaporation is made speedier with the addition of a heater. This is hidden away in the sealed base compartment. It has 110V of power, and is designed to be used hooked up to a power supply at an RV park or dock.
Even so, the rate of evaporation will be limited. The surface area of the evaporation chamber isn’t huge, and the heater has limited power. So you’ll need to make sure there are arrangements to deal with any overflow. Connect the drain pipe to a smallholding tank for safe disposal.
The capacity here is suitable for one person using the toilet regularly. If you’re putting it somewhere where it will be used only occasionally, it will work for three to four people.
As with many other composting toilets, this isn’t the most attractive. The finish is a shade of beige unappealingly called “bone”. But let’s face it – going to the loo when you’re on the move is something of a novelty. So perhaps the unusual appearance is less of an issue here.
What We Like
What We Don't Like
If you’ve looked at our reviews and still aren’t sure which is the best composting toilet for you, read on. We’ll take you through the questions to ask yourself before you make your final choice.
How hands on are you prepared to get?
There are some great designs out there, but from time to time they all need human intervention. So ask yourself what you’re prepared to do.
Some toilets separate out urine from hard waste. That means the compost stays drier and tends to be less smelly. But it also means that you’ll have to empty out containers of urine. Both Nature’s Head models reviewed here will require you to do that.
If you’d rather avoid it, there are other options – but they may mean more work upfront.
If the toilet will be near a sewer, look for one that can be connected to your wastewater drainage. The Villa 9215 from Separett would be a good option in these circumstances.
But if your loo is going to be away from mains services, consider digging an evaporation bed. The Sun-Mar Excel-NE works well with this approach. And there are comprehensive instructions on the website on how to do it.
Contemporary bathroom or off-the-grid cabin?
Are you planning on putting your loo in your main bathroom? Or is it going to be a weekend home where the focus is on getting back to nature?
Aesthetics may not be the first thing that spring to mind when you’re considering which toilet to buy. But remember that you’re going to have to look at it often, especially if it’s in your main home. So consider how it will fit into its location.
Some of the toilets on our list really don’t look like conventional loos at all. If you want to proclaim your environmental credentials in your off-grid cabin, they’ll work like a charm. Consider the models from Sun-Mar or Nature’s Head.
But if you’re looking for a toilet to blend into a contemporary bathroom, you’ll find your choice is more limited. Separett’s Villa 9215 is streets ahead of its rivals here.
What about your power supply? You won’t need mains electricity, but most toilets come with an electric fan as standard or as an optional extra. If you’re going to be somewhere with mains electricity, take advantage of that. Separett’s toilet can be used with either an AC or DC supply.
Temperature is important too, as composting slows down in cold weather. If your toilet will be located somewhere cold, look for an option with a heater. And in very cold spots, you may need to be prepared to add a separate heater too.
How much outdoor space do you have?
Think about your space requirements outside as well as inside.
Do you have room for a separate evaporation bed? If not, you’ll need a toilet you can connect to a sewer or holding tank, or comes with urine containers.
And remember that human waste needs a long time to degrade sufficiently to be used as compost. That’s particularly the case if you’re a meat-eater. You’ll need a composting area to empty your solid wastes and allow the process to continue. Leave it for around two years before use.
Who will be using it?
Different composting toilets will have different capacities. Consider how many people will be using the lavatory. Will they be using it daily, or just on the weekends?
Check out the size of the liquid and solid waste containers, and consider how often you’ll have to empty them out. For higher capacity situations, the Excel-NE from Sun-Mar is well worth a look. If you’re a single, regular user, consider the toilets from Nature’s Head.
And if you’ve got children, the optional child’s seat available with Separett’s Villa 9215 may make this a good choice.
Ready to choose?
We hope you’ve enjoyed our round-up of the best composting toilets available today. This is still an evolving market, but there’s a lot of variation between the different models.
Our top pick is the Nature’s Head toilet with the spider’s handle. It’s easy to install, with no need to worry about digging evaporation beds. And the full-sized seat is comfortable and practical too.
Whichever option you choose, you’ll know you’re saving water and power. And you won’t be flushing away toxic chemicals. Even better, with careful use you’ll have a free supply of compost for a lush, green garden!
My name is Peter Weeks, Writer of The Daily Gardener. Gardening has always been my passion, nothing gives me quite the satisfaction that feeling the soil sift through my fingers does. Give me a spade, a shovel, and a rake, and I can happily while away the day transforming a patch of land into a beautiful oasis. To me, gardening is life. It’s not a career. It’s not a job. It’s something that I truly love doing. It’s a way of life, a passion that I’ve no intention of ever giving up.