Do-It-Yourself Graywater Pond

Using Graywater

• Building a graywater pond provides a reservoir from where you can pipe water to your plants or allow it to evaporate, thereby reducing the quantity that enters the sewer system. Graywater should be used only in subsurface irrigation and not in surface sprinkler systems. The particles of skin and soap provide fertilizer for the soil but are a source of potential health hazards if exposed on the surface.

Excavation

• Dig the hole in which you will create the pond to the depth and shape you want. Your pond needs to accommodate all the graywater you produce, or it will overflow. Calculate the quantity of graywater produced by your household and the amount that will flow out of the pond on a daily basis, to determine the size of pond you need. Choose a stable location, and excavate the full size of the pond. If you plan to locate the inlet pipes out of sight, dig a trench approximately 6 inches deep from the outlet drain to the pool.

Building

• Cover the base of the hole with a large sheet of builder’s plastic or rubber pond liner, cut to fit. This will prevent seepage from the pond into the surrounding earth, which could destabilize the pond. Depending on your budget and the size of the pond you require, position in the hole a children’s plastic wading pool, an old bathtub or a fiberglass pond mold. Fill in the sides between the plastic and the pool shell with premixed cement, and allow it to dry. Place rocks or decorative stones around the outline of the pond to give it a neat profile.

Water Inlet

• Place 2-inch-diameter black plastic tubing in the bottom of the trench, and join the lengths with connectors. Alternatively, your piping need not be buried and can lie along the surface of the ground. Connect one end to the outlet pipe at your bathroom drain, and cut a circle in the plastic pond liner through which to pass the other end. Connect it to the pond infrastructure using an inlet valve or by passing it over the side of the pond and fastening it securely. Test the flow to make sure that the water is moving easily through the pipe from the drain to the pond.

Water Outlet

• Attach several pipes to the side of the pond. Run the lengths to the plants you intend to irrigate with the graywater. Perforate the pipes with small holes along the lengths to allow water to flow out along the route of the pipe, watering any plants that are located conveniently.