A standard plumber has the skills to perform the inside portion of your greywater system. They have the skills to cut in a 3-way diverter valve to the drain pipe of your showers or sinks, and can send the pipe outside. However, most plumbers are not familiar with 3-way diverter valves because they are typically used for swimming pools, and so may want to use another method of greywater diversion. We advise you to request a 3-way valve as it’s the easiest for the user.

Many plumbers do not have landscaping skills, nor experience with greywater, and may not feel comfortable or interested in the outside portion of your system.

If working with a conventional plumber for the inside portion of your system there are a few things to talk with them about.

  1. Conserving elevation. Keep the greywater pipes as high as possible so they can exit the house over the foundation.
  2. Keeping the greywater separate from the blackwater until the greywater pipe exits the house. There is no need to plumb the greywater and blackwater in separate pipes (“dual plumb”) all the way to the main sewer line.
  3. Installing a 3-way valve to capture the greywater in a readily accessible place. You can show your plumber diagrams such as these to explain what you need: (from the book, “Create an Oasis with Greywater” ) Diagram 1   Diagram 2

A word of caution:

If you are sure you want a simple system be sure to communicate that to your plumber (or contactor). Some plumbers or contactors who haven’t had much direct experience with greywater systems may have a tendancy to create an overly complicated system that probably won’t work as well, or will take more maintenance than a simple system. It won’t hurt to ask if they have a greywater system in their own home!