Off Grid Home Forums Technical Discussion greywater system Re: greywater system


I have a rainwater catchment system, where water on my acrylic Earthship roof goes to galvanized(never PVC!) gutters with top shields to keep out some of the leaves and pine needles. The two downspout “T”s have a 1/16″ mesh butyl glued to the metal, going down to an ABS pipe siliconed at the junction and wrapped with expansion bubble plastic through the top Earthship wall course. 4”, going to a “T” then elbow down to a junction piece with screen on bottom, multiple rubber banded so it can be removed and cleaned periodically. It goes to the top 16″ round hole of a 425 gallon pickup bed poly tank with a screen on top of the opening, up in its own cabinet 2′ above the floor. A flex pipe goes through the top (to near the bottom of the tank) and out to a ShurFlo 12VDC pump(on switch), to a copper 1/2″ pipe that goes under the floor to a “T” at the vanity. There it goes to a filter that takes out everything for drinking water at the vanity, with drain to a garden. The other end goes to a drip system in the front garden. The tank has a 2 1/2″ pipe with valve to get water for putting into 3 gallon garden waterers. There is a 2 1/4″ pipe at the top for overflow to the floor drain connected to the foundation and overflow drain in the front garden, out to a rock pit well in front of the main house. This is not the same as the grey water systems in the highly informative middle link at larrydgray’s site and the earthship site.

The Earthship site has a sand filter in a ground level or lower tank, with toilet bowl type valve to a pump to another, higher tank. From this second tank grey water is used for interior gardens (by gravity flow), or taken by pump through several filters and a UV device to a pressure tank for household re-use. Whether that water can be used outside for gardens or livestock depends on your local codes.

I know one of the problems with the filters is detergent buildup and grease from dish washing. Some systems have a “Y” valve to separate the greasy or detergent filled water to the black water system(two water drainage systems). With clothes washing, the detergent can be eliminated with green wash balls that really work great. The Staber washing machine can run on modified square wave power, does not cause much lint, uses only 135 W/hrs, and 15 gallons for a large load.

We have a deep well for the main house, but illegal to use for garden watering. I put a bath tub next to one 1.6 gal. flush toilet, and one bath gives us nearly a week of flushes(with a 1 gallon pitcher). The other laundry/bath has a shower with low flow head, and another 1.6 gal. toilet, for when two are needed.

The Earthship greenhouse/guesthouse outbuilding has a Biolet NE composting toilet, with solar shower hook over the floor drain.

Rainwater catchment from a non-toxic(metal, acrylic, tile, or concrete) roof can be used for exterior gardens and livestock, in most cases (check your local regs).