The Best Composting Toilet Review

The best composting toilet is an essential consideration for anyone living off grid, or for people looking to reduce their environmental impact.

Best Composting Toilets:

How Does a Composting Toilet Work?

Self composting toilets work by using organic carbon-based matter like sawdust to create air pockets within the storage compartment and improve the ratio of carbon to nitrogen which makes conditions better for composting . This means microscopic organisms break down the contents to create compost.

That might not sound the nicest concept of waste disposal – but all compost is made from rotting organic matter. That organic matter returns nutrients and minerals to the earth where they fuel new growth in plants as a natural fertilizer.

The by-products of this process are heat and a slow release of some gases. Hence the best composting toilets come equipped with extractor fans – essentially just like a computer fan – to vent the composting toilet and carry any gases outside.

The combination of these means the contents shrink over time and so the best composting toilets can take weeks before they need emptying. The Sun Mar Excel composting toilet produces 2 parts of compost for every 10 parts of waste that go in.

How to Use a Composting Toilet

Make sure to follow the instructions of whichever self composting toilet you go for. In general composting requires everyone to sit down because of the required urine separation which generally happens at the front of the bowl. This means a slight change in habit for the gents.

After depositing any solids you should add a handful of your chosen carbon material – hay, coconut hair, sawdust etc. Many RV composting toilet brands offer their own material optimized for use with their toilets.

For other types of RV toilets see our guide here.

The urine tank – if you have one such as in Nature’s Head composting toilets – will require frequent emptying about every couple of days depending on usage.

And don’t be too frightened about emptying self composting toilets – the end product should largely resemble normal compost. Although be sure to use appropriate washing and hygiene precautions. If left for long enough a lot of harmful pathogens actually die off, but that will probably take longer than this primary stage in the toilet.

When emptying a composting toilet, assume the waste is still potentially harmful. Check your local regulations about disposal as most states specify how this can be carried out – often as simple as burying it under a little soil. You should not use this compost for growing food.

Composting toilets are an ideal solution for anywhere without a water supply. That makes them a great camping toilet or self composting toilet for RV users but their most common use is on boats.

That’s why brands like Nature’s Head use the traditional sea-faring term of “head”. This term dates to when sailors would go to the toilet by hanging in the rigging at the bow – or head – of a sailing ship.

What Makes The Best Composting Toilet?

Urine Separation

One of the key design features of a compost toilet is separating solid and liquid waste. This urine separation means solid waste doesn’t get waterlogged and so is allowed to decompose with the addition of loose material like sawdust.

The urine needs to run off into a separate container that is emptied much more regularly. Some composting toilets allow you to divert urine into the ground. This is great for a long-term structure but isn’t so great for an RV toilet or boat toilet and so the effectiveness of the urine container is of key importance. It needs to be sealed, odourless and leak proof but equally it needs to be removed easily for disposal.

The urine container needs to be emptied every other day depending on usage and so the quicker and easier this is the better your off-grid life is going to be.


The composting process actually requires some heat so those microbes can thrive. In a cold climate you may find a composting toilet doesn’t work so well. Therefore try to make sure your composting toilet is installed in a way that maximises its composting potential.

Does it matter if it freezes? No, but it will slow the process. The composting will simply pause in freezing conditions and restart when the temperature improves. On the other hand, no one likes a freezing toilet seat anyway.

While you may prefer to keep a composting toilet outside or in some sort of outhouse, the extractor fans in these designs ensure you can keep them in the warmth.

On that subject…


Needless to say, a composting toilet that has issues with odour isn’t going to convert anyone. While the process itself is fairly odourless it remains that a sealed design with an extractor fan is important – especially in a confined space like an RV toilet or a boat.


How much do composting toilets cost? Unfortunately they can be quite expensive. They are quite a niche market so the designers and manufacturers need to make a living somehow. Plus there’s a lot of engineering that goes into them. The build quality also needs to last as a boat toilet is going to endure a lot of hard conditions throughout its lifetime. A lower price is always better as long as you know the product is going to deliver effectively.


It’s always amazing to look back and remember when Amazon was just a bookshop. You never thought you could buy a toilet on there, and certainly not a composting toilet! These are the kind of niche-products you would normally have had to travel to buy or request a catalogue for. However, all the best composting toilets seem to be avilable on Amazon. In fact, plenty are Prime-elligible!

Composting Toilet Reviews – The Best Composting Toilet For You?

Nature’s Head Self Contained Composting Toilet

Nature's Head Self Contained Composting Toilet

The Nature’s Head Composting Toilet is an aboslute market leader and perhaps the best composting toilet.

Nature’s Head composting toilets were designed by two long time sailors who sought to create a more user friendly version than anything else on the market, since traditional composting toilets tend to be little more than a bucket with some sawdust.

Instead, Nature’s Head aim to produce composting toilets that resemble regular toilets with sturdy materials and an odour-eliminating design.

The Nature’s Head composting toilet system attaches to the floor with two small l brackets. There is one ventilation hose to run outside and one 12volt power hook-up for a small computer type fan.

One of the most succesful design principles of the Nature’s Head composting toilet system is in diverting uring to a separate chamber that is easy to empty. This keeps the solid matter dry so that it can decompose effectively and the longer it is left the better the compost produced.

While the urine container should be emptied every other day, the solid container should last about 80 uses before needing to be emptied.

The Nature’s Head composting toilet also comes with a five year manufacturer guarantee. As this is clearly designed for people willing to build and maintain the fittings in their lives, they stress that most problems should be fixable with little more than a screwdriver.

The bad news is that composting toilets of this style are never going to be a seamless replacement for a plumbed in toilet.

Cleaning the composting toilet in general is required and its tough. You will probbaly need to take the three pieces apart and hose it down or give it a good clean once a month or so.

Make sure to rinse out the liquid bucket every time you empty it or staining will build up fast.

Nevertheless compared to a standard septic tank or RV toilet the increase in messiness isn’t that great.

Separett Villa 9215 Composting Toilet

Villa 9215 Composting Toilet

The Villa 9215 is perhaps the best composting toilet for anyone concerned about dealing with waste. That’s thanks to a simple design that uses compostable bags as the solid storage. Otherwise the composting toilet works much the same as the Nature’s Head with an electric extractor fan and urine separation.

When you sit on the seat, a flap opens up to allow access to the solid receptacle. Otherwise this remains covered so liquid just runs off. You never actually see the waste as it stays in the bag which could be a big bonus.

However, the Villa composting toilet is definitely not the best for boats or as an RV toilet. It doesn’t have a urine container – just a pipe that runs off. That’s great for a more permanent placement where the hose can be buried in the ground.

Sun-Mar Excel Non-Electric Self-Contained Composting Toilet

This Sun-Mar composting toilet is almost certainly the best self composting toilet for a fixed location. It’s built for a much greater amount of use and doesn’t need electricity. Instead it uses the same technology as a traditional chimney as it recommends installing the rear vent with a pipe up and out of the roof so that a very small amount of wind creates negative pressure within the compost toilet.

The Sun Mar Excel uses a “bio drum” technology that means there is no separation of solid and liquid. Instead all the contents go into the same drum and a hand crank on the front means this can be stirred for optimum composting potential. You should turn the crank clockwise every two days or so.

However, what makes the Excel the best composting toilet system is the drawer at the bottom. Small amounts of contents drop out of the biodrum when cranked and into the drawer for a second stage decomposition process. That means with normal use the Sun-Mar Excel only has to be emptied once every four to six months. The resulting material is thus far more like compost than human waste.

Sun-Mar GTG Composting Toilet

Sun-Mars Composting Toilet

This toilet is extremely well built. Pay careful attention to the dimensions as while it is intended as an RV toilet it is particularly large. Like the Villa composting toilet you can use a bag to line the solid compartment, but unlike the Villa it does have a proper container for urine and so it works as a boat and RV toilet.

One of our biggest concerns about the Sun-Mar is it lacks a lot of the features of the best composting toilets and yet still carries a high price tag. While it’s a good solid construction that wouldn’t look out of place in your bathroom at home, the urine separation is just a hole at the front that empties into the urine container and a big hole into a bucket underneath for solids.

It’s a cheaper option but lacks a lot of the frills that make the best designs feel more like thriving and less like surviving.

Leave a Comment

Your email address will not be published. Required fields are marked *