Here’s a system for re-using sink water to flush a toilet. It claims to save about 10 gallons/ person per day.
http://www.watersavertech.com/AQUS-Water-Conservation.html
I have a client that has a failing septic system. The system has been repaired twice before, he's run out of "repair area" and is currently using a leach bed built by one of the best installers in the area. It will take between 50-75% of the water he uses in his 3 bedroom house, and the rest is comes up to the surface. I figure I need to reduce his water use by about 120-160 gallons per day, or come up with another way of disposal.
Normally I could use two buried single-pass sand filters in series to treat the septic tank effluent, chlorinate, de-chlorinate, aerate, then dump it to a creek. Except the creek is classified as zero-flow so the State won't allow this unless I look at all other possible alternatives.
Funny rules that we have here- if I separate out grey water and use to water his lawn and shrubs I have to treat it well beyond the simple sand filter scheme above. A multi-pass sand filter won’t do it either. I’m thinking that I’ll have to go off the shelf, high tech. Does anyone have experience with a unit that can do this?