Parts of a Gravity Greywater Irrigation System
A) Washing machine: Laundry machine can be located outdoors or indoors, near an exterior wall.
B) Greywater standpipe: Laundry discharge hose is placed in this pipe, labelled “GREYWATER,” for discharge into greywater garden. Sewer drain pipe is maintained for manual switch to sewer if desired.
C) Wall penetration: 2 ½” hole in wall for painted ABS pipe, caulked around pipe edge.
D) Greywater pipe: Typically run underground at ¼”/foot slope to discharge greywater to garden. This pipe can be branched to provide multiple outlets.
E) Backwater valve: One-way flap valve at pipe outlets prevents anything from entering the pipe.
F) Mulched, vegetated basin: Heavy mulch acts as a filter for solids in greywater and retains moisture longer for plants. Greywater recipient plants may include non-edible desert shrubs or trees and fruit trees or vegetable plants where the greywater does not touch the edible part of the plant.