How to Install a Graywater Irrigation System

In this video, This Old House plumbing and heating expert Richard Trethewey shows how to reuse laundry wastewater.

Steps:

1. Install a three-way diverting valve to wall behind washing machine.

2. Connect discharge hose from washing machine to bottom port on diverting valve.

3. Cut and assemble PVC pipe and fittings to lead from left port on diverting valve to utility sink.

4. Use Drill/driver and 1-inch-diameter hole saw to bore a hole through exterior house wall.

5. Cut and assemble PVC pipe and fittings to lead from right port on diverting valve through hole drill in house wall.

6. Install a vacuum breaker to the T-fitting on the right side of the diverting valve.

7. Assemble the PVC drain line down to the 1-inch-diameter high-density polyethylene tubing that leads to the irrigation system.

8. At each plant to be watered, cut into the 1-inch-diameter irrigation tubing and install a ½-inch x 1-inch T-fitting.

9. Connect a short length of ½-inch-diameter tubing to the ½-inch outlet port on the T-fitting.

10. At the end of each outlet tube, spread a thick layer of bark mulch.

11. Drill a hole in the side of an old plastic flowerpot. Insert the outlet tube into the hole in the flowerpot and place the flowerpot on top of the mulch bed.

12. Fill in around the flowerpot with more bark mulch.

13. Adjust the diverting valve to send graywater either down to utility sink or out to irrigation system.