Ask This Old House episode: Learn how to construct a simple laundry greywater system. Learn the basics of how to construct a laundry-to-landscape greywater system from his Old House plumbing and heating expert Richard Trethewey and greywater expert Laura Allen.
Google Tech Talk: How to Implement a Greywater System for Your Garden. Presented by Laura Allen and Gregory Bullock. This video covers basic information about greywater systems including costs, codes, system types, and plant friendly products.
Greywater 101: Washing machines and happy raspberry plants. This short video tours a laundry-to-landscape system (Note: This system was installed pre-code change in California, when all simple greywater systems were illegal. To be code-compliant under the current code the outlets need to be covered, see the Ask This Old House video for how to do that. This system is code-compliant in states that allow surface irrigation.)
Greywater Systems Overview by Tucson Water. This video includes details on how to install a gravity-based branched drain system.
Laundry-to-landscape video by Art Ludwig of Oasis Design.
To view all greywater photographs go here.
4. Brochures and Handouts
- From Laundry to Landscape: Tap Into Greywater. Five page article in Mother Earth News by Laura Allen and Cleo Woelfle-Erskine.
- General studies
- Graywater Awareness and Usage Study. Prepared for the Soap and Detergent Industry. This study summarizes the results of a large, national survey including incidence of greywater usage, usage rates per region, why people use greywater, how they are using it, and demographic information. They found 7% of household in the US were using greywater, with highest concentration of users in the Southwest and West.
- Critical Review: Regulatory Incentives and Impediments for Onsite Graywater Reuse in the United States. By Zita L.T. Yu et. al. Published in Water Environment Research, July 2013. This review covers regulations, barriers, and incentives for greywater regulations in the 50 states.
- Study of the effects of on-site greywater reuse on municipal sewer systems. By Eran Friedler, Israel Institute of Technology, 2011. This study looks at how wide-scale use of greywater could impact municipal sewer systems. Researchers concluded the sewers would not be negatively affected.
- Long-Term Effects of Landscape Irrigation Using Household Graywater: Literature Review and Synthesis by Larry A. Roesner et al. 2006 WERF. This literature review identifies the current state of knowledge regarding the long-term impacts of landscape irrigation with household graywater and identifies the knowledge gaps that need to be addressed in an experimental plan.
- Studies on soil and irrigation quality
- Residential Greywater Irrigation Systems in California: An Evaluation of Soil and Water Quality, User Satisfaction, and Installation Costs, by Laura Allen et. al. This is the largest study of real greywater systems to date in the United States. This study looked at 83 systems in California and tested soil constituents, greywater quality, plant health, user satisfaction, maintenance requirements, and installation costs. See the study webpage for key findings and download links.
- Long-Term Study on Landscape Irrigation Using Household Graywater – Experimental Study by Sybil Sharvelle et. al. 2012, WERF. This study looked at four existing greywater systems and three newly installed systems (in four states), as well as greenhouse applications of greywater. They monitored soil constituents and plant health. Some of their findings include: Most plants were healthy with long term irrigation of greywater and that greywater systems increased levels of sodium in the soil in the older systems, but not to a level of concern for plant health. They didn’t find greywater having a consistent effect on the levels of E. coli or enterococci in soil, contamination was inconsistent and also found in soil samples irrigated with fresh water. They also observed increased infiltration rates in both field and greenhouse studies, concluding that long-term greywater irrigation may increase soil infiltration rate.
- Greywater Characterization and Treatment Efficiency. Final report for Massachusetts Department of Environmental Protection by Peter Veneman et al. University of Massachusetts. 2002. They studied commercial greywater systems and analyzed the water quality. They also tested soil columns effectiveness at treating greywater and found that “disposal of greywater into a soil-based medium has considerable benefits in regards to purification.”
- Reuse potential of laundry greywater for irrigation based on growth, water and nutrient use of tomato By R.K. Misra et. al. 2010. Study compared sources of irrigation on tomato plants and found, “These results suggest that laundry greywater has a promising potential for reuse as irrigation water to grow tomato.”
- Reuse of Domestic Greywater for the Irrigation of Food Crops. Thesis by Sara Finley Department of Bioresource Engineering, McGill University. 2008. This study examined the benefits and risks associated with domestic greywater reuse for the purposes of vegetable garden irrigation. Treated and untreated greywaters (and tap water) were used to irrigate individually potted plots of lettuce, carrots and peppers in a greenhouse. Upon maturity, plants were harvested and the edible portions tested for fecal coliforms and fecal streptococci, common indicators for the presence of pathogenic microorganisms. Even though both fecal coliforms and fecal streptococci were present in the greywater, no significant difference in contamination levels was observed between crops irrigated with tap water, untreated and treated greywaters. Plant growth and productivity were unaffected by the water quality. These results reinforce the potential of domestic greywater as an alternative irrigation source.
- Plant growth and microbiological safety of plants irrigated with greywater. By Lumka Salukazana et. al.(National Research Foundation – University of KwaZulu-Natal, South Africa.) This presentation summarizes the results of a study monitoring plant growth (leafy and root crops) irrigated by greywater and microbial analysis of the exterior and interior of the crops. Researchers concluded that greywater provided nutrients for both leafy and below-ground plants, that there was no significant difference in microbial quality of greywater irrigated crops relative to controls and commercial crops, and that greywater represents a potential resource for food production.
- Health studies
- Graywater Pilot Project: Final Report. City of Los Angeles, Office of Water Reclamation Nov, 1992. Summary: This study tested greywater and greywatered soils from sites with in the city. They concluded that the soils in the test areas were already contaminated with animal feces so the addition of greywater may be irrelevant. They also found that total coliform indicator bacteria increased with greywater application. This study also tested for actual disease causing organisms (salmonella, shingella, and entamoeba histolyctia), which is uncommon in greywater studies, and they didn’t find any in any of the greywater.
- Greywater Data and Calculations Spreadsheet. Oasis Design, 2009. Summary: This spreadsheet synthesized data from various sources to estimate 1) the degree of exposure to greywater systems (a billion greywater system user-years in the US in the past 60 years, the 2) the prevalence of diseases that are potentially greywater transmissible, based on reporting to the CDC (five million), 3) the number of these infections that were attributed to greywater (zero).
- San Francisco Graywater Design Manual. Excellent how-to manual, authored by Laura Allen and created by the San Francisco Public Utilities Commission. Free download.
- The Water Wise Home: How to Conserve, Capture, and Reuse Water in Your Home and Landscape by Laura Allen. Comprehensive how-to design and build residential greywater systems. Includes step-by-step construction details.
- The New Create an Oasis with Greywater Choosing: Building and Using Greywater Systems — Includes Branched Drains Revised and Expanded 5th Edition by Art Ludwig. Excellent resource from the inventor of the popular laundry-to-landscape and branched drain systems.
- Water From the Sky by Michael Reynolds. This book about Earthships details their indoor, build-in greenhouse greywater systems that grow indoor plants year round while filtering the water to be used to flush toilets.
7. Suppliers and Other Organizations
On-line vendors of greywater parts:
- Cleanwater Components: Sells kits to build a laundry-to-landscape system, diverter valves, and kits to install automatically controlled diverter valves (actuator).
- Pentair Ltd.Sells “never lube 3-way diverter valves”.
- HD Supply: Sells double 1/4 bend (flow splitters) for branched drain system.
- Oasis Design: Sells flow splitters with clean-out installed and diverter valves.
- Oasis Design: Informational website from Art Ludwig, the originator of the laundry-to-landscape and branched drain systems.
- Central Coast Greywater Alliance (Santa Cruz). Leads classes and trainings in the Monterrey Bay Area.
- Sweetwater Collaborative: Leads workshops in Santa Barbara.
- Watershed Management Group (Tucson and Phoenix)
- Occidental Arts and Ecology Center: Offers an amazing permaculture design course located at a site with many greywater systems.
- Water Now. Non-profit offers greywater trainings in Marin County.