Re composting heads, we are definitely having them on our new cat. For liveaboard
cruising they are definitely the way to go.
There are only 3 possible downsides to composting toilets which are,
2. time between emptying
3. possibly cost
Bug invasion is when tiny flies use the composting mix as a home and they reproduce, like most insects, quite prodigiously. This is fixed by having fine insect mesh on the breather pipe. Not mosquito mesh, the mesh that will keep out sand flies, noseeums, gnats, that fine mesh.
Also the flies can come from the source of the composting media if you use peat moss etc. The best seems to be to use the dried coir (coconut husk) bricks which don't contain the fly eggs/larvae to begin with.
The time between emptying is determined by how many people are making regular "deposits". If it is 2 or 3 people, it should be a month or more before you need to dump the contents and start a new batch of compost media. If you regularly have lots of guests contributing to the head
, then you will have to empty more frequently and the mix will not have had enough time to break down and compost.
The cost is somewhat more than a run of the mill manual flush head
, or about the same as a good electric
I am reliably told by those who have "been there - done that" who have had to work on a regular head to fix choke valves or whatever, that you only ever want to do that once, hence our attraction to composting toilet.