Typical Components

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Collection Plumbing

Graywater must first be separated from the rest of the sewer, or blackwater, before reuse. Here are the types of components used to collect (or divert) graywater:

  • Three-way diverter valve: A valve that allows graywater to be diverted either to the sewer/septic or graywater system.
  • Dual plumbing: When installed during new construction or a plumbing remodel, the 3-way valve can control all the graywater by collecting it in one pipe. This is called dual plumbing,
  • Other than the diverter valve, collection plumbing is plumbed with standard plumbing parts following standard plumbing methods.
Distribution Plumbing

The method of distribution depends on the type of graywater system. Below are examples of common systems.

  • In a laundry-to-landscape system, graywater is distributed in 1” pipe and tubing, and released through 1” x ½” tees.
  • In a branched drain system, graywater is distributed in 1 ½” or 2” rigid plastic pipe, and divided up using flow splitters called double ells.
  • In an unfiltered pumped system, graywater is distributed in 1” pipe and tubing, and 1” x ½” tees.
  • In a filtered pumped system, graywater is first filtered, then pumped for distribution through 3/4” mainline irrigation tubing. Then graywater drip irrigation tubing, such as IrriGRAY tubing (requires 400 micron filtration) or Bioline graywater drip tubing (requires 100 micron filtration) is used.
Preparing the Landscape for Graywater


In simple low-tech graywater systems, the landscape needs proper preparation to receive graywater. Unfiltered graywater, from a laundry-to-landscape, branched drain, or pumped (no filter) system, will contain particles that can clog the soil. Untreated graywater must be distributed onto mulch, such as wood chips, where particles are filtered as water soaks into the ground.

In filtered systems, most of the particles are removed, so graywater can be distributed into soil. California requires subsurface irrigation for graywater, meaning that the graywater outlet points should be covered in at least 3” of mulch.

Indoor Use Components

Systems that send water back inside for toilet flushing will require additional components to disinfect the water after filtering. When stored, graywater has an odor. Disinfection helps reduce odor and prevents bacteria from growing in the water. Some of these systems use chemical disinfection. Systems using chlorine may have chlorine odor.

In the US, high-end systems are usually custom designed, and use various filters and then UV disinfectant. International companies, like Nubian Oasis and Pontos Aquacycle, use proprietary filter mediums and UV disinfectant.

Please see our Waterwise Business Directory to help you find seasoned graywater design and installation professionals, as well as needed components.