Dustin on Ingas Water System
to water theme!
would also consider the water from the roof of the building - could go into the pond for use in the house.
grey water from washing - that could first be used for the toilet flush, and then
final grey water - into a septic tank?? (needs maintenance!!, honey sucker or similar)
or opt for a dry toilet system - no water, only a doubled tank, with a 'mobile' seat, and the two holes are used only for some months each!! you need a good ventilation system above roof!!
in this case water will be completely separated from toilet!!
Greywater: if only natural detergents, soaps and similar (no oil or other similar residues from kitchen) natural drainage can work. Dig a hole and fill with stones and pebbles and let the water drain and filter naturally.