In all our years of boating, from our first sailboat and its complete lack of functional plumbing to our little cuddy cabin fishing boat with its disgusting porta potty, we’ve seen it all. Buckets, proper marine toilets, the most expensive electric heads, and even the various alternatives to toilets, like those fancy composters. Which is best, and which is right for your boat — or van or RV?
This is a quick guide to the choices you have, along with some recommendations based on our experiences. We’ll look at some of the smallest composting toilets available and how they stack up against their competitors and the lowly porta-potty.
Best Small Toilets for Small Spaces in Boats, Vans, and RVs
While larger yachts have plumbing that rivals nice homes, you’ll find a wide variety of toilet situations on small boats. From the basic bucket to proper plumbed systems, here’s a look at what you’ll find in off-grid toilets for small spaces.
Marine Porta-Potty
Small boats, like fishing boats and trailer sailers, are usually outfitted with porta-potties. These are simply plastic toilets with built-in tanks that hold the “goods” until you can empty them into a bathroom on shore. While on the boat, they are generally fine to use — they’re sealed to keep odors at a minimum, and they function much like a regular toilet. Some even include a water tank for a little cleaning flush after each use.
The problem comes when it’s time to empty it. The seat separates from the tank, and it usually has a pour spout to make the process as painless as possible. But it’s a disgusting, odorous task, and one that’s full of messy splatter potential if you aren’t careful.
Using a porta-potty isn’t that bad if you’re taking it home. Emptying in a public or marina bathroom might be awkward, and some marinas we know ban the practice. On the other hand, a few have outdoor stations where you can empty them. It helps to be able to empty it in a bathroom (hopefully, one with a powerful exhaust fan!) and then wash the whole porta-potty with a garden hose in the yard.
You can buy various chemicals to mask the odor and make it less unpleasant. You usually add a little to the tank before using it. Nothing makes it smell nice, but it’s at least a little less nasty.
Composting Toilets vs Porta Potties
The smallest composting toilets you use for travel are not composters at all. They are separating toilets, meaning they have two containers, one for liquids and one for solids. There are pros and cons to this system.
The most significant benefit of this system is that it keeps the smell down. It’s the combining of the two that makes DEFCON ONE-level nasty sewage. If you keep the urine separate, it won’t smell much. And, if you keep the solids in their own contain and try to dry them out, maybe by adding dry soil or sawdust, then the smell is usually negligible.
The smallest composting toilets are super simple. They have a special seat that funnels the liquids into their own canister. On most portable toilets, there is a rubber flap on the lid of the liquid container to minimize splashes and smells.
The solids bin requires you to sprinkle in some sort of medium — the most common on boats is coconut coir since it packs small and is bug-free. Coconut coir is available online — it’s usually used as a soil medium for gardening. This sprinkle-after-you-use system is called the layering method.
Larger composters get fancier. You half-fill the toilet with your composting medium (coconut coir) when the toilet is empty. Then, some sort of stirring apparatus, electric or with an exterior handle, mixes it all up inside the toilet. These larger toilets usually also have an exhaust fan to help dry the solids and keep the smell down.
No matter what type of composter you have, keeping bugs out is the biggest problem. Small toilets emptied and cleaned frequently (i.e., every week or less) aren’t as much of a problem. Larger toilets attract more bugs, so they must be completely sealed to prevent anything from laying eggs in there. The most common culprits are tiny fungus flies (they look like fruit flies).
When it comes time to empty and clean your composter, how you do it will depend on the type of composter you have. If it uses the layering method, you usually tie the solids bag closed and dispose of it like any other household garbage. The liquid container is emptied in any toilet.
Toilets with a churn handle do not have bags, so you must empty it into a trash bag first. In my experience, this is the messiest, nastiest, worst step. I’ve since moved on from this style of composter. Your mileage may vary, of course!
Standard Marine Sanitation Systems
If you have space, the standard boat system consists of a marine toilet (or head) plumbed into a holding tank. Remember, it’s illegal to discharge sewage anywhere near shore or inland, where most of us spend our time boating. To legally discharge raw sewage, you’d need to be three miles offshore, but you’d need to go farther than that in many places. A holding tank lets you keep the sewage onboard until you get to a dock with a sanitary pump out. Many marinas have them.
The problem with this system is that you must have easy access to the pump out, and not everyone does. Further, most boats have small tanks, so you need to pump out frequently. And then there’s the system’s complexity, which is prone to clogs and odors.
If you want a complete education on marine toilets, the problems, and how to keep one in good working order, read Peggy Hall’s book “The New Get Rid of Boat Odors: A Boat Owner’s Guide to Marine Sanitation Systems.”
Run-Down of the Smallest Composting Toilets
Here’s a list of the smallest composting toilet options on the market today, whether you need a small toilet solution for your boat, van, car camping setup, or RV.
Trelino Origin and Evo Toilet
The best part of the toilets made by Trelino is that they come in various sizes: small, medium, or large. This means you can pick and choose the right size for your small space. Of course, the smaller the toilet, the less it holds, and the more frequently you must empty it.
The Origin toilets are made of robust rotomolded plastic with wooden lids, while the Evo line is made of a sleeky but thinner ABS in either white or grey. Both are easy to clean and super portable. Be sure to read my full review of our Trelino Evo composting toilet.
The smallest composting toilet that Trelino sells is the Origin XS (extra small). It measures 380 x 300 x 290 mm (15 x 11.8 x 11.4 inches). The liquids jug holds 4.5 liters, while the solids bucket holds 6. The company says this is enough for six to eight uses. You can purchase the XS on Trelino’s European websites, but it might be hard to get in the US.
The EVO and Origin S models (small), which measure 13.0 x 15.4 x 11.7 inches and 13.6 x 15.7 x 11.9 inches, respectively (W x D x H), are available in the US from Trelino or Amazon. It has tanks of the same size as the XS above. All Trelinos are built in Germany.
Boxio Toilet
Boxio makes a line of plastic, modular furnishing for outfitting whatever small space you’re traveling in, but they’re primarily aimed at camping. They also make a camping sink and a matching storage box. The idea is that, no matter where you are, you can set up a bathroom out of these boxes. They’re perfect for micro campers like teardrops, car camping, van lifers, or even open fishing boats that don’t have a place for these facilities.
The Boxio Toilet base measures 11.81 x 15.75 and is 11 inches high. The liquids and solids containers are 5.7 liters each, which the company says should last you between eight and ten uses. The Boxio Toilet-Up is a separate bin that elevates the toilet about five inches more to a more comfortable level. It also stores your new compost medium (they provide hemp) and a handy shaker.
The Boxio sells for only $180, while the Toilet Up is $35 more. In the world of composting toilets, it’s a steal. It’s made in Germany.
Trobolo Toilet
Trobolo makes a few simple composting toilets, plus parts to allow you to DIY one yourself. The plastic toilets are called the WandaGo. The WandaGo Lite base measures 13.4 x 15 inches and is 11.8 inches high. The regular WandaGo (not Lite) is the same unit but with a plastic storage container underneath to make it taller, just like the Boxio. The liquids hold 4.6 liters, and the solids hold 6.5 liters.
The DIY option is appealing if you have a small or uniquely sized space, like some boats. You’d lose the portability, but all you’d need is a shelf you could place the seat on and buckets under. This might allow you to utilize some under-seat location in your van build or an oddly shaped corner of your boat’s head compartment.
The DIY set is available in small and large containers and includes the diverting seat (provide your own lid) and solids and liquids containers.
OGO Composting Toilet
The OGO is a newer design, and I’m not going to lie — it’s pretty fancy. This is an auger toilet where you half-fill the solids container with medium and leave it alone until it’s full. The mixer/churner on the OGO is electric — you just push a button. It also has a light that tells you when to empty the liquid container.
The standard, full-size OGO sells for over $800 and is much larger, so it’s competing with the Nature’s Head or Airhead composting toilets. It measures 16 x 15 x 18.5 (W x D x H). The solids bin holds 25 to 30 uses, and the liquids hold 2.4 gallons (9 liters).
OGO also makes the OGO Nomad a smaller, cheaper separating toilet built to compete with the little ones above. It measures 15.4 x 13 inches and is 12.38 inches tall. It sells on Amazon for $199. OGOs are made in the US.
Nature’s Head Composting Toilet and Airhead Composting Toilets
These two brands are the OG boat and RV composting toilets, both having been on the market for decades. Compared to newer designs, they are larger and more complicated to clean.
However, they have a few features that might still make them worthwhile for some. For example, they are the only brands with available notches cut out of the back, allowing it to sit closer to the curved side of a boat’s hull than a squared base would allow.
The Nature’s Head composting toilet is available on Amazon, while the Airhead can be purchased directly from the company’s website. Both sell for more than $1,000 and share a similar set of features. Ultimately, the right one comes down to which best fits your space. For reference, the Nature’s Head measures 19.02 x 20.98 x 20.98 (W x D x H).
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