Composting toilets
Are an interesting concept that MAY have a future aboard, but not yet. Although there are some smaller ones on the market, the only ones that work are too big to fit in most heads, and nobody's figured out a way to make 'em smaller yet, because the composting drum has to be big enough to give the material room to "fluff" and aerate when it's rotated--which, btw, has to be done every 2-3 days...which is ok for liveaboards, but can be a problem for "weekend warriors" who may even skip a couple of weekends in a row. But even if those problems can be solved, 90% of what goes into any toilet is liquid...and since wet soggy organic material does compost, it rots and stinks, excess liquids have to be drained off and there are usually more of 'em than the evaporator can handle. They can't legally drain overboard, so that means at least a small holding tank--which puts you right back where you were when you started looking for an alternative to a head & holding tank. And there are other issues too....even human solids are mostly water, so it's necessary to add a cup of dry organic material--peat moss is the material of choice 'cuz it breaks down quickly--to each "flush"...that means carrying a supply, and finding storage room for it. The evaporater needs power to run the fan and warming plate (the non-electrical units are totally unsatisfactory), though not a lot, and it can use 12v instead of 115 AC, but anything that continuously draws power creates an issue on sailboats. And where to run the 3" vent stack can be a problem too. Those are the minuses...the pluses are, when installed, operated and maintained according to directions, there's no odor...the finished compost is sanitary and dry--almost identical, except it's human instead of animal--to the bagged dry manure found at garden supply stores, and it's usually months before the drawer needs to be emptied because composting reduces material to about 10% of its original volume. Sun-Mar makes the best ones...for complete specs and descriptions of how composters work, check out their website at: http://www.sun-mar.com
