Landscape Plants Benefit From Household Greywater

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 greywater irrigation and may receive benefits beyond just having their thirst quenched. Greywater—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 greywater for their irrigation needs, it is important to understand what compounds are in greywater, what happens to them in the environment and what potential impacts greywater may have on soil quality, groundwater quality and plant and human health.

This study evaluated both existing and new household greywater irrigation systems in Arizona, California, Colorado and Texas. While soil irrigated with greywater 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 greywater irrigation. In addition, results from a greenhouse study showed that nitrogen present in greywater was beneficial for plant growth. It is possible that fertilizer addition can be reduced or eliminated where greywater is applied for irrigation.

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