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Gray Water for Vegetables?

A forward-thinking gardenerd wrote in this week:

“I am considering a gray water system to use on a vegetable garden. Is this safe to do? If so, is it considered organic?”

My first thought was, no – it’s not really safe to use, but it might be with the right system.  Then I took to the cyberspace waves and found a few bits of information:

In many states it is actually illegal to use gray water on vegetable gardens.  You should check with your municipal sewage service to see what laws apply where you live.

In states where gray water systems are legal, they are becoming more sophisticated, to the point that you can divert only certain types of waste water from your home to the yard.  For example, collecting water from the kitchen sink or dishwasher isn’t such a good idea because of the food particles and such, but you might want to re-use the water from your bathroom sink or shower.  Assuming that you use all-natural, bio-degradable soaps and detergents, this water can be safe to use on plant matter, but I’d still stay away from using it on veggies.

As far as whether it is considered “Organic” or not, I was searching the USDA website for information about gray water, and found nothing.  I do remember that our organic standards were at risk several years back, when the government was trying to soften the laws to include sewage sludge as an acceptable form of irrigation and fertilizer.  My colleagues and I fought that one long and hard.

The bottom line is that untreated gray water is generally not recommended for use on vegetable gardens.  I don’t know a vast amount about gray water systems, or the improvements that are being made every year, but hypothetically speaking if you have a way to treat the water before it goes out to the garden, there may be a way to use it in vegetable gardens.  If you are considering installing a system, I would grill your installer about the safety features and treatment process before considering it safe for use out there in the food factory.

Here is a website that has some more information about gray water systems and uses in the home:

I hope that helps.  Thanks for writing in.
If anyone out there has a gray water system or insight about this question in California or any other state, share it with us here.

This Post Has 6 Comments

  1. Christy Wilhelmi

    Wonderful!  Thanks, Melanie.  I love having pros on board.

  2. Melanie Winter

    Having worked with Steve, I can recommend him highly! In case he doesn’t check back in, I’ll take the liberty of posting the link to his company’s website.

  3. Christy Wilhelmi

    Thanks for the comment Steve.  We really appreciate your input.  This should help our gardenerd make an informed decision.  If you have any websites that help people do graywater installation right, we’d love to have you post them here.

  4. Steve Bilson

    I entered the greywater irrigation business in 1990 and sponsored California’s greywater law in 1992 (Assembly Bill 3518), worked on the implementation code with virtually every public agency and interest group in the state for 2 more years, then sponsored the law for multi-family, commercial, institutional greywater irrigation systems (AB313) in 1995, and worked on that code with everyone for another 2 years. I’ve worked on other state codes as well. My company now has more legal greywater irrigation systems out there than all other companies combined. I’ve eaten many fruits and vegetables from greywater-irrigated gardens. It’s safe as long as you wash the edible first, as you probably would with anything from the garden. Human pathogens sometimes found in greywater don’t become systemic in plant life, but they can come in contact with tubers and reside on the exterior walls. Simply washing them off does the trick. As for Santa Monica being in the forefront on greywater irrigation, wrong. They are far from it now that they’ve hired a stodgy old fart from the old-school plumbing inspection community as their in-house plumbing consultant. I’d fought that idiot every step of the way during the state legalization process and he lost at every turn, though his “sky is falling” mentality did manage to delay inplementation of the code past the last drought, when everyone was finally paying attention to our state’s precarious water situation. That momentum was lost until recently. It’s terribly unfortunate that Santa Monica gave him another forum for his archaic viewpoint, as the community there really means well and deserves better. Legal greywater irrigation causes water conservation, increased irrigation efficiency, wastewater reduction, run-off elimination, decreased energy demand, and smaller carbon footprints. Most of those benefits accrue to the state. Not bad for something that takes no subsidies, just a willing partner in the permit department.

  5. Christy Wilhelmi

    Thanks, Rachel.  Santa Monica is on the forefront of enforcing gray water systems for new construction.  It’s a great start to decreasing run-off and pollution on the streets and in the ocean.   

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