What is Greywater?
Greywater is used water from sinks, showers, baths and washing machines; it is not wastewater from toilets and can be safely used for outdoor irrigation! By re-using laundry water, residents can conserve water and reduce the energy, chemicals, and costs involved in treating water to drinking water (potable) quality.
The easiest way to utilize greywater is with a Laundry-to-Landscape (L2L) system. Creating a Laundry-to-Landscape greywater system in your home can play a critical role in drought resilience given its ease in both installation and maintenance. In efforts to reduce potable water use for irrigation purposes, there have been recent changes to the California Plumbing Code regarding gravity-fed greywater that make it easier for residents to create their own L2L system.
Basic Greywater Guidelines
Greywater is different from fresh water and requires different guidelines for it to be used safely:
- Do not store greywater (more than 24 hours). If you store greywater the nutrients in it will start to break down, creating bad odors.
- Minimize contact with greywater. Greywater could potentially contain a pathogen if an infected person’s feces entered into the water, so your system should be designed for the water to soak into the ground and not be available for people or animals to drink.
- Infiltrate greywater into the ground, do not allow it to pool up or run off. Knowing how well water drains into your soil or the soil percolation rate of your soil will help with proper design. Pooling greywater can provide mosquito breeding grounds, as well as a place for human contact with greywater.
- Install a 3-way valve for easy switching between the greywater system and the sewer/septic.
- Match the amount of greywater your plants will receive with their irrigation needs.
More Information on Greywater
- For more information about greywater guidelines and types of systems, visit http://greywateraction.org/contentabout-greywater-reuse/.
- Click here for a free downloadable greywater design manual.
- Click here for California State requirements for no-permit greywater systems.
- Click here for California Plumbing Code regarding greywater regulations.
