There is a lot of misinformation about composting toilets, spread by people who have never had one. Here I go again ...
Gary, if your friend had a smell problem, he was doing something VERY wrong. If composting toilets have one great benefit, it's that there is ZERO smell. Ask anyone who has one on their boat. You can pinch a proverbial loaf, turn the handle a few cranks and then open the trap door and stick your nose inside and there is no smell. You can come to your boat after being closed up for the week and you won't find ANY smell, at least not from the composter. Even if you don't hook up the fan there is no smell. The fan is to help dry and aerate the compost. Also, I find it hard to believe the guy spent 900 bucks on a composter, uninstalled his marine head and installed his composter only to give up on it after 2 days!
The other thing is the bowl is sanitary. The solids drop into a chamber below and don't touch the walls of the bowl. At first I thought it would take some special aim (with a few brown scrapes on the sides), but it is something anatomical. You just sit and it falls in the right place. In two years and many guests, not once has anyone missed! The urine is directed to a small channel at the front of the bowl and only requires a misting of vinegar and water to keep it clean. So, just to put the issue to rest- there is nothing unsanitary about the bowl (swab away if you like).
That doesn't mean there is no down side to a composting toilet. You still have to dispose of the urine jug (for us, daily, for others perhaps every 2 or 3 days). I just dump it over the side before I go to bed every night. It's sterile and don't we all pee off the rail anyway? The solids you have to dump every month or so (living aboard) or perhaps as little as every 6 months for weekend use. Remember that the solids are drying out into almost nothing so over time the volume doesn't increase if the use is limited to weekends. Again, unless you are very squeamish, dumping the solids is no big deal: just put a trash bag over the box and turn it over. It looks and smells like dirt. No big deal for most people. I actually dump mine in the jungle (not where people will walk) or at sea when well off shore. You have so many options for dumping with a composting toilet, including a garbage bag and the dumpster. Is a composting toilet "strange" for people used to a flush toilet? Yes, but the short learning curve is worth the effort for the many benefits.
What are the benefits? As I see them, they are:
Safety: You remove 2 through hulls and the potential for sinking they represent. I read somewhere that the single greatest cause of boat sinking is the seawater toilet (back siphoning being a big one!).
Space: You gain a lot of space when you remove the holding tank
, hoses etc. The footprint of the composting toilet is the same or even less than a water toilet. It's just a bit taller.
No odors. (see above)
Many options for managing your waste (see above)
Simplicity. Nothing can break, leak, explode etc. The absolute worst that can happen is that urine gets into the solids chamber (a male guest standing to pee a few times in a night of beer drinking). This turns the composting chamber into a wet mess that can smell. The solution is to just dump the contents and fill with fresh coconut fibre and you're good to go again. Compare this "fix" to the typical "toilet disaster" involving a regular marine toilet (blocked toilet, pump
leaks, holding tank
leaks, stinky hoses to change etc.).
Price. A Nature's Head or Air Head is going to run you about 900 bucks or less. That's it. Add all the various plumbing bits, holding tank
, toilet etc. of a wet head and see what comes out cheaper.
I won't get into the ecology debate as it will just incite arguments. One can make a pretty good argument for the composting toilet being much more ecological, especially if you dispose of the compost in your garden or in the woods (and not in the dumpster).
A final word about them is this: if you are contemplating installing one on your boat you owe it to yourself to get opinions from people who have one installed. Visit a boat with one, talk to the owner and do a little research and see what is involved in using one in real life. Composting toilets are not for everyone, but you won't find many (almost any!) people with regrets who have installed them. I know of exactly THREE cases of people un-installing theirs (C&C being one). If you have a specific question, there are a few Sailnetters here with them, myself included.