I'm not really sure what sort of topics I should be posting in this, it being the gray water section and septic tanks being black water and all, so I'll simply present my situation (bearing in mind I am still something of a newbie to the permaculture scene, please forgive my ignorance - we're all here to learn and exchange info, right? ):
I have a parcel of land I'd like to build a cob home on in Klamath County, Oregon. When I purchased the land I had been planning on using incinerating and/or composting toilets as an alternative to a septic system and using my gray water to water the garden. The problem(s) I'm running into are two-(or three)-fold: In order to get a building permit, the county requires a septic tank already be installed on site (which is, of course, its own permit and test). This is naturally infuriating since what I had been looking at does not require one, but due to the terrain there is also a very strong possibility that a standard septic system will not work. The bedrock, of basalt, has a depth that varies between 18 inches to 7 or 8 feet beneath the soil. The usual alternative to a standard septic tank presented was a Cap & Fill and a sand filter. Frankly, from what I understand of it, this is simply not an option. Never mind the crazy expense of around twelve grand.
Needless to say, I am strongly interested in any alternatives that would satisfy the Oregon code (and county) which is not as expensive as a Cap & Fill (or sand filter). Do you have any advice?
Thanks for your query. That's exactly the sort of question I get here all the time. Basically: I want to do one thing, and all of the legislation seems to point in a much more expensive direction… and my site is challenging. Help!
Well, http://www.deq.state.or.us/wq/onsite/onsite.htm suggests that you can adopt "Alternative Treatment Technology", but on a very quick search of their website on http://www.deq.state.or.us/wq/pubs/factsheets/onsite/ATT.pdf, exactly what constitutes ATT is not fully defined. It's possible that you could adopt a reed bed or constructed wetland system as an ATT approach to deal with the septic tank effluent if you so wished. But that would still be followed by a percolation area of some sort - which will bring the costs up again.
If you're a permaculture newbie, I'd just like to throw in a comment about the incinerator toilets. My understanding of these is that they consume fairly vast amounts of energy per annum. David Holmgren's Permaculture Principles 9 (Use small and slow solutions) and 5 (Use and value renewable resources and services) would have my permie self saying that if you can employ naturally occurring bacteria in the soil to filter your effluent; or the many natural processes in constructed wetlands and reed beds, then you'll end up with a solution that should cost a lot less to run and be a lot kinder to the Earth.
That said, you already mentioned a compost toilet. Principle No.3 (obtain a yield) springs to mind with this one. If you can put in a really good compost system that is pleasant to use, easy to work and safe for the local environment, then you'll avoid the large cost of a septic system and recoup good compost for your garden. This is a big area though. Don't jump in without doing a good bit of research first. Visit friends who have a good system. Investigate the limitations and how to deal with problems that may arise. When selecting a system to buy or use, remember that more expensive does not necessarily mean better or easier to use!
There is a USEPA factsheet on compost toilets that may help your case. http://water.epa.gov/aboutow/owm/upload/2005_07_14_comp.pdf It's not singularly positive, so it may or may not provide enough reassurance to local administration. Joseph Jenkins' Humanure Handbook is an excellent resource on the subject - dealing with one particular type of compost system. I've got a different type of system here at my own house, but Jenkins' approach is wonderful.
For grey water I'd recommend that you look at http://oasisdesign.net/ for guidance and ideas. They have a really effective looking, low-tech approach that I love. You could also use a constructed wetland or reed bed for grey water, prior to infiltration into the ground in a way that protects the local environment.
Your next steps are:
1 research into the topics raised here to clarify what you want;
2 approach your local authorities to see if what you want is permissible;
3 design and implementation.
Let me know if you have any questions on any of the above.