The 4 key points when training a plumber to install a greywater system

Feb 14, 2014 | John Bell

If you’re a building engineer getting ready to install greywater recycling systems, you will be happy to learn that it is a fairly simple process. It is important that the system be installed before the drywall goes up so that the pipes can be routed properly. Here are the basics your plumber will need to know:

1. Isolate shower/bath drains

Greywater needs to be isolated into the system. Kitchen greywater must be avoided completely. Laundry greywater can be used but only if a filtration system is installed before it enters the recycling system. It’s best to avoid laundry greywater if possible. Isolate the drains from the shower/bath setups and tie them together with 2” ABS piping in the main floor ceiling. Run the pipe to the mechanical room where the recycling system is stored. This will isolate the greywater for recycling.

2. Install toilet supply lines

After the water is processed in the recycling unit, it must run to the toilets. As the water is non-potable, all lines must be purple pex or labeled with marking tape that reads “non-potable water – do not drink.” One ½” to ¾” pipe is plumbed from the unit as a riser before branching off to the toilets.

3. Install overflow lines

Two overflow lines must be installed back into sanitary. The first runs from the inflow pipe to the main building drain as a bypass in case the system is overloaded. The system will also have a vent pipe/overflow outlet that connects to the same drainage line. These will prevent excess greywater from backing up into the system.

4. Install vent line

A vent line must be installed like any fixture. The system can be tied to the most convenient vent line in the mechanical room.

Additional considerations

If a manual bypass is chosen, a backflow preventer will be required.

It is a fairly simple process but the system must be installed before the drywall goes up so that the pipes can be routed properly (click to see schematic). We are here to assist you and your plumber but keep these four steps in mind when preparing for the installation of your Greyter System.