Graywater 101: Using Graywater to Green Plants?

Sponsored Post from: The American Cleaning Institute

“Graywater” is a term bandied about by those in sustainability circles and a topic we’ve touch on frequently at Earth911, but many still have questions about exactly what graywater recycling is and if it’s really safe for the environment.

So, what’s the verdict? Is this idea green or gross? Earth911 took an in-depth look at the subject to give you the basics and answer all of your most pressing questions about this unconventional recycling tactic.

Graywater 101

If you’re unfamiliar with this type of recycling, the No. 1 question on your mind is likely: What is graywater, anyway?

To put it simply, graywater is water from bathroom sinks, tubs, showers and laundry washing machines. Despite frequent confusion, graywater does not include water from toilets, kitchen sinks and automatic dishwashers (this is called “blackwater”) and has not come into contact with food and human waste, either through kitchen sink food waste disposal or flushing toilets.

Graywater may contain traces of dirt, food, grease, hair and certain household cleaning products. While Graywater may look “dirty,” it is a safe and even beneficial source of irrigation water, according to the advocacy group Greywater Action (The spellings of “greywater” and “graywater” are often used interchangeably in discussions about this topic).

As potable water supplies become more limited throughout the world, there is a growing interest in innovative approaches to water resources sustainability, and household graywater reuse for residential landscape irrigation is a potential solution that’s slowly picking up steam.

Graywater recycling offers scores of benefits; plants can beneficially utilize the constituents found in graywater as valuable nutrients. However, the use of such systems has not yet become widespread due to uncertainties about the safe use of graywater, according to a report released by the Water Environment Research Foundation in partnership with the American Cleaning Institute.

While some states have begun to legalize and regulate the practice of graywater reuse for residential landscape irrigation, little guidance based on scientific data has been provided for the safe operation of graywater irrigation systems and the potential effects on plant health after graywater is applied.

“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 health,” said Kathleen Stanton, ACI’s Director of Technical & Regulatory Affairs.

The WERF/ACI project began in May 2008 and went on for more than four years. The aim: to provide scientifically-based data on the use of graywater and its impacts on soil quality and plant health. It also tried to address public health concerns stemming from potential exposure to elevated levels of E.coli and product ingredients in soils where graywater has been applied. Read on for the details.