This webpage serves as a resource for information regarding the use of greywater as a water supply, which can offset the use of potable water supplies to meet household and commercial needs.
Historically, "graywater" is defined as water generated from domestic activities, including showering, bathing, and washing laundry (but not from toilets or kitchen sinks, due to the risk of contamination). The use of untreated graywater is limited to subsurface irrigation of outdoor plants.
However, in regions where water supplies are unreliable because of drought, water right conflicts, or other issues, interest exists in making greater use of graywater – considered a reliable local resource – for household and commercial purposes.
For instance, communities in Australia are now using graywater treatment systems to collect, store, treat, and disinfect graywater so that it may be used for surface irrigation, as well as for flushing toilets, washing laundry, and other indoor activities.
To expand the indoor and outdoor uses of graywater in the United States, research is needed on the regulatory, operational, and public health aspects of both treated and untreated graywater.
The resources below are a work in progress and will cover a wide variety of interests, such as local codes, permitting, equipment testing, public health protection, environmental considerations, costs and benefits, case studies, and others. Please note that these resources are provided for informational purposes only.
This 2009 news article discusses about how graywater can positively impact our lives.
This 2009 Southern California Environmental Report Card was prepared by the UCLA Institute of the Environment.
- Graywater: UCLA gives Southern California a mixed grade
Related to the above link to the report card, this 2009 Los Angeles Times blog article discusses the benefits of graywater reuse.
This 2010 news article discusses how a Los Angeles community is practicing the reuse of water from sinks, showers, baths, and washers.
This 2009 article, which advertises a particular greywater treatment system, includes information about the beneficial applications of a graywater system to a household. Please note that NWRI does not endorse any product or organization.
Information on Treatment:
This document discusses how graywater systems can be an effective tool for conserving water. Prepared by the Washington State Department of Health, 2007.
- New South Wales Guidelines for Greywater Reuse in Sewered, Single Household Residential Premises (PDF)
This 2008 document provides guidelines for reusing graywater in an urban setting. Prepared by the State of New South Wales (Australia) by the Department of Water and Energy.
This 2009 white paper discusses the applications of untreated graywater, as well as regulations set by various states, including California and Arizona.
Organizations with Information about Graywater:
- Greywater Action
- Wholly H2O - California's Integrated Water Reuse Management Center
- The Greywater Alliance
- Colorado State University - Graywater Reuse and Rainwater Harvesting