Composing toilets do not really compost, they simply dry out solids

By Dan McCarty

Pittsboro, NC – I have never used a composting toilet but I have done quite a bit of research on them for use on boats.

composting toiletComposing toilets do not really compost, they simply dry out solids. If you left the contents of the toilet alone it would eventually compost but that is not how the toilets are usually used.  These toilets really just desiccate the solids by keeping out urine and using material for the drying process.  Liquids are diverted to one container and solids are in another with the material to aid in drying,

Urine is what causes smells, not solids, so the desiccating toilets I have read about separate the liquid and solids and of course this minimizes what needs to be dried.  Users of the desiccating toilets say the smell, if any, is earth like.

Some people use peat moss for the drying material but it can have bugs. I have read information that leads me to believe there might be sterilized peat moss so that bugs/eggs are not present. What seem to work best on boats is Coir which is made form coconut shells and used in potting mixes and such. Ironically, Coir has to be moistened a bit prior to use but a small, compressed amount can last for months which, along with no bugs, is why Coir is popular on boats. Some people say that saw dust works well too.

There are many conversations about composting toilets on the Cruiser Forum which is a site that discusses living and traveling on sailboats. A composting toilet has some pretty good advantages on a boat.  Here is the latest discussion and there are plenty more of them about this subject on the website.

There are three companies that are mentioned frequently on the cruising forum:


Some of the links I provided, if not all, have videos that discuss the toilets

I like some of the C Head models because they use a standard five gallon bucket for the solids and a one gallon milk/water jug for urine. The other brands use their own containers that would be problematic and expensive to replace.  You can pretty much find a five gallon bucket and a one gallon water/milk jug anywhere.

What to do with used toilet paper should be considered with any of the designs.

So what does one do with a full bucket and jug? In the boating world, it depends. If off shore, where dumping is allowed, it is easy. In a no discharge zone, the solids are usually tossed in a dumpster at a marina. The solids can be mixed with bleach if needed. Urine can be poured down a toilet. In a remote shore area, some people bury on land as if you were camping but I don’t think many people are in that situation. Most are dumping offshore or at a marina.

I don’t know what one would do on land for disposal.  I hear some people put it on their flower beds but not gardens. This stuff is not composted and should not be used as composted material for a food producing garden.

I would bet that this is more than most Chatham Chatlist readers wanted to know about composting toilets.