i've just finished reading this great book on composting crap:
humanure handbook by joseph jenkins. we've been talking about composting toilets quite a bit recently in the design comet and land use (we've actually talked about them for about seven years!) and this book has really helped me understand what's involved in properly composting.
i have received word from our engineer that if we employ composting systems for our solid waste that we can reduce our water treatment system size by 35%. this translates into between $5,000 and $10,000 of savings. it also makes a lot of sense ecologically. not passing
humanure into our water treatment stream means the system has to work a lot less, won't need replacing as soon and provides destiny with a stream of manure for gardens.
we will have to get a special permit to put the manure on the ground, but the tide may be turning on all of this as water and resources become more expensive. the us department of health has given its nod and some states have acknowledged the value in finding alternatives to the flush toilet. this becomes especially salient when you consider that only 3% of the planet's water is fresh water and that 2/3 of that is frozen. so, only 1% of the planet's drinkable water is free and about 1/5 of the human population lacks access to it. now consider that about 45% of water used in american households is to flush toilets and you can begin to see how wasteful our current sewage system is. our consumption runs very much along the lines of our consumption of fossil fuels: reckless and unsustainable. if everyone on the planet had a flush toilet we'd very quickly have no drinking water.
so, for destiny, i'd like to float the idea of eliminating all the flush toilets. the privy, which is currently designed as a double vault storage system into which feces and urine simply collect and decompose anerobically (a.k.a. stinkily) could be replaced by simple to build and very inexpensive composting toilets. farm and wilderness camp in bridgewater, vermont has such a system and obtained permits to "dispose" of their compost on site. if we stay with a privy, we would have to hire a septic hauler to pump it, which amounts to a big toilet flush (and expense) because the waste gets sent to the municipal waste treatment center and subsequently dumped in a river.
the one flush toilet in the kitchen could be replaced by some kind of composting arrangement. it also may be possible to eliminate the kitchen toilet altogether. the privy or composter (whichever happens) will be handicapped accessible and capable of handling all of destiny's poop. we ended up with a toilet in the kitchen originally becuase the state requires one near any "restaurant" kitchen. it's still not clear yet whether destiny's kitchen is a restaurant kitchen, but a toilet facility in the kitchen building also serves as a cold-weather option and a more easily handicapped accessible option, so it probably makes sense to keep it. but, we've always talked about it as a low use station and i don't think it makes sense to lose $5-10k in saving for the priviledge of flushing especially if it's use is going to be discouraged at gatherings.
the reduced water flow may also impact our well and reduce cost there. we may be able to use smaller components both in the pump and storage system as well as the solar system.
i will be talking further with our engineer and researching myself the rules and regulations in vermont. it can be frustrating talking to state wastewater folks because they're bound by lots of rules and information that are proving to be less than ecologically sound. the past few years here in white river junction there have been mishaps upstream with sewage treatment that causes notices to go out discouraging swimming in the river. in larger cities this happens much more often. for instance, in los angeles, between 1993 and 2002, there were 3000 sewage spills. it's baffling that this kind of thing is seen as acceptable while simple and safe composting is seen as a threat.
there's lots more info on composting that i'll pass along later.