The toilet in a boat is called a head, and composting toilets are called Composting Heads; in a boat.
We have successfully used a composting head for about 7 years now and feel that they are very easy to use and work really well in a full time cruising boat. This means that they will work especially well in a weekend or day sailboat!
In this video, we go into depth talking about the specifics and all the ins and outs of a composting toilet!
Composting toilets work very well, Maddie and I both use ours everyday and I dump it every 6 months! The reason I dump it at 6 months is not that it "needs" to be emptied, but because I think that it has been long enough and it is "time to do it".
I'm going to spare you the pictures of emptying it, but "most" of the container is filled with a rich black dirt. Then there are some "fresh" additions to the pile that haven't broken down yet. Dumping it is easy. I place the container in a dock cart with a bag over it and carry it over to the dumpster. Then I dump the container into the trash bag and place the trash bag in the dumpster. Easy and mess free!
Then I let the container sit in the sun for a few days to "dry and air out". Luckily, it doesn't smell, so Maddie lets me dry it out in the cockpit of the boat. After everything is good and dried out, I begin the filling process again.
The instructions that came with my toilet (by Natures Head) state careful measurements of how much dirt you need to add, and how often you need to add more dirt. Just like with the Dickinson Heater, the supplied instructions are much more complicated than they need to be.
I simply fill the bottom up to the crank with peat moss, then I add diatomaceous earth to the peat.
The diatomaceous earth comes in a 4 pound bag from a hardware store. Diatomaceous earth is very safe to use. In the United States it is marketed as a pesticide, but outside of the United States it is used to treat stomach issues by eating it. Diatomaceous earth works as an absorbent which helps settle upset stomachs and runaway intestines by absorbing whatever is irritating the area and passed in a more controlled manner.
When mixed in with the peat, it acts as a mechanical pesticide by drying out the fats and oils in the insects exoskeleton. Poop and peat makes a wonderful breeding ground for gnats and flies, add some diatomaceous earth and no insects will thrive!
I just dump half the bag (approximately 2 pounds) into the peat and turn the crank until the lot of it looks grey in color.
The rest of the diatomaceous earth fits nicely in an old container of pretzles, with a secure screw on lid. This will prevent acidental spills in the locker while heeling over or being tossed around by the seas.
For the next six months, no further soil or peat is added to the solid container. I simply turn the crank after every use and empty the liquid container when it is near full! While explaining how to use a composting toilet is "interesting" to some guests, never needed to repair a blocked joker valve because they flushed something they shouldn't have is awesome! I've been using a composting toilet for over 3 years now, and this is all I have to do every 6 months.
Most boats have a holding tank system which keeps your poo in a smelly soup. We keep our poo in dirt!
When I bought Wisdom, it had the standard marine head with septic hoses running everywhere. The hoses were old and reeked of toilet wastes. It seemed that no matter how much I cleaned them, they always smelled. The head was rather old and after rebuilding it a few times, I decided to ditch the traditional method and convert over to a composting toilet.
The way it works is the solids and the liquids are kept in separate areas. The liquid tank fills up rather quickly and needs to be dumped weekly. The solids tank actually lasts a very long time. With two people using it, we choose to dump it every 6 months. It is not full, nor in need of being dumped at 6 months; we simply feel that it has been long enough. When we dump the solids tank, it doesn't look like a pile of poo. Instead, it looks like dark dirt (though I wouldn't put this on the vegetable garden)!
The composting toilet we chose is very comfortable to sit on and use, and it fits well in the boat. I did drill a weep hole in the section that holds the pee bucket so that shower water would drain out.
Installation was also very straight forward. Remove the old head and all associated plumbing, then attach the compost toilet to the sole. The kit includes fans and hoses and all sorts of attachments to the toilet, but we decided to try it out as it is first, then install the rest of it if we felt the need.
Two years later, we still haven't felt the need to install the other parts. The head sits in our head/shower and quietly serves its purpose without much intervention.
But what about bugs and flies? Well, that is where the dirt comes into play. We found that using pure peat moss and poo was a wonderful breeding ground for gnats and flies. By mixing in a fair amount of diatomaceous earth with the peat moss, nothing would spawn. We mix the diatomaceous earth in until the lot of it takes on a grey color, that seems to do the trick!
If the pee bin ever begins to smell, we simply pour in a cap full of white vinegar. That will neutralize any smells instantly, once again restoring peace to our floating home.
The boat began to smell much better once the heads were switched. Removing the old smelly poo hoses and replacing them with the compost made a huge impact on the quality of life below deck!
Since these composting toilets work as standalone devices, they would also work great in cabins, RVs, and other boats.
