I'm building a house, probably this summer, and after some reading decided composting toilets and graywater systems were the way to go.
The county Health Inspector didn't think so. He said they only approve composting toilets in places where septic systems will not work.
If this is a brick wall (and we have regular streams of guests who might be offput by alternative systems anyways) How do you reform a "legal" septic system?
I know trees like willows destroy septic systems - I was wondering if a comfrey pasture on the leach field (I farm animals) was the friendliest option. I live in a very sandy but fertile area in West Michigan.
Also, dormant (winter) plants probably don't metabolize much Nitrogen...
If you're going to submit to the system enough to do the conventional toilet and septic, why not just let the inspector leave the site, and then set up, in addition to it, whatever simple compost system you want? I'd start with a geriatric toilet seat and a 5 gallon bucket, with buckets being taken out to a compost outside. Pee in a separate container when possible, and you can then decide whether to put this into the compost or use it elsewhere. The whole shebang is easily shifted into hiding when anyone comes around to whom it would be a problem. I did humanure in an apartment for ten years this way.
I would do it similar, maybe a bit more conventional, like a bought composting toilet system. The greywater is not a big deal as long as you leave the kitchen out, apparently fat clogs the soil. There is a book build an oasis with greywater. Simply plan in a way that the plumbing is accessible and high enough that you have the gravity. Then after you have moved in and everything is finished do the greywater job, not a big deal.
Unfortunately I have no experience which compost toilet system would be good.