Most Landscape Plants Benefit from Watering with Household Graywater: New Research Finds

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New research funded by the Water Environment Research Foundation (WERF) in collaboration with the American Cleaning Institute (ACI) finds that many plants around the home do well under long-term graywater irrigation and may receive benefits beyond just having their thirst quenched.

Coupling WERF’s credible, well-documented peer review process with collaborators such as ACI enables WERF to answer questions the public has about graywater reuse.

New research funded by the Water Environment Research Foundation (WERF) in collaboration with the American Cleaning Institute (ACI) finds that many plants around the home do well under long-term graywater irrigation and may receive benefits beyond just having their thirst quenched. Graywater--wastewater primarily from bathing and laundry--makes up nearly 50% of a typical household’s wastewater and could supply 100% of the residential irrigation demand in some areas of the country. As more households turn to graywater for their irrigation needs, it is important to understand what compounds are in graywater, what happens to them in the environment, and what potential impacts graywater may have on soil quality, groundwater quality, and plant and human health.

This study evaluated both existing and new household graywater irrigation systems in Arizona, California, Colorado and Texas. While soil irrigated with graywater showed increased levels of surfactants (surface active agents) , antimicrobials and sodium compared to those irrigated with freshwater, only three salt-sensitive tree species (avocado, lemon and scotch pine) out of 22 plant species investigated showed negative responses to long-term graywater irrigation. In addition, results from a greenhouse study showed that nitrogen present in graywater was beneficial for plant growth. It is possible that fertilizer addition can be reduced or eliminated where graywater is applied for irrigation.

“ACI’s mission is to support the sustainability of the cleaning products industry through research, education, outreach and science-based advocacy. Through partnering with scientific organizations such as WERF, ACI continues to promote good stewardship of its industry’s products and ingredients,” said Kathleen Stanton, ACI’s Director of Technical & Regulatory Affairs. “Coupling WERF’s credible, well-documented peer review process with collaborators such as ACI enables WERF to answer questions the public has about graywater reuse,” continues Jeff Moeller, WERF Research Program Director.

The report “Long-term Study on Landscape Irrigation Using Household Graywater-Experimental Study (06-CTS-1CO)” is available for download at http://www.werf.org and on ACI’s Science website at http://www.ACIscience.org. A web seminar on the subject is scheduled for October 17, 2012, registration is available at http://www.werf.org.

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The Water Environment Research Foundation, a nonprofit organization formed in 1989, is America's leading independent scientific research organization dedicated to wastewater and stormwater issues.

The American Cleaning Institute® (ACI – http://www.cleaninginstitute.org) is the Home of the U.S. Cleaning Products Industry® and represents the $30 billion U.S. cleaning products market. ACI members include the formulators of soaps, detergents, and general cleaning products used in household, commercial, industrial and institutional settings; companies that supply ingredients and finished packaging for these products; and oleochemical producers. ACI and its members are dedicated to improving the health and the quality of life through sustainable cleaning products and practices.

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Carrie Capuco

Brian Sansoni (ACI)
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