Homepage 2019 » Forums » Water Sustainability » Greywater Systems

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    I have heard conflicting information that greywater should only be used to water non-food producing plants and that it can be used to water veggies and such. So which is it? Is it that you have to run the greywater through a series of non-food producing planter beds and the discharge water is then used to water food producing plants?



    I know that Malibu won’t allow you to use grey water for even lawns!

    I saw a documentary…can’t remember which one…and it noted that grey water should only be used on non-food plants.

    I saw that the Las Vegas area uses grey water that filters through a created estuary with gravel/sand, bacteria, sunlight and water movement as the purifying elements to make it safe for drinking….they also treat the final product before use.

    When you find out the answer to this question post it here so it can be shared. thanks. 🙂



    Hi, in England I can’t find any info on how to treat grey water to make it safe to use on food plants. If it is stored for more than a few hours it becomes really smelly and full of bacteria that we don’t want. We don’t have room for a reed bed system so any info on how to treat it would be great!



    On The Permaculture Podcast I listened to a man tell a story of how it was difficult to teach the group he was working with in Africa about different techniques because they were constantly ill. He investigated the premises to find a cistern full of the communities waste water with mosquito larvae in it. He suggested a grey water system that would feed the water into (I believe) a series of banana circles (or maybe it was one big banana circle?). It accomplished 1) teaching fundamental permaculture techniques, 2) teaching basic grey water system installation, 3) double/tripling the extent a bucket of water could be utilized, 4) improved the healthy living conditions of the place, which 5) improved the health and well-being of the people, and finally 60 yes, they also ate the bananas produced from the grey water system.

    Of course, the bananas you eat never need to touch the water they grow in. So you need to ask, What is the worst possible level of contamination in my grey water system? What parts of the plants you water will you eat? What level of risk are you willing to take? Though some governments don’t agree, it’s important that we don’t equate grey water with sewage. Frankly, I think putting manure in your garden is no different, probably more contaminating, than anything coming from you sink.



    Carissa, I didn’t hear that podcast, but it sounds like that wasn’t technically a ‘greywater system.’ People usually use the term ‘greywater’ to refer to the result of washing clothes, dishes, etc. It is distinguished from ‘blackwater’ in that greywater does not have raw sawage (poop and pee) in it.

    Again, I don’t know the details, but it sounds like the water in that well was a mixture of groundwater (which was presumably clean at one point in the recent past?), greywater (water from washing clothes/dishes/bodies), and blackwater (poop and pee). It’s extremely common for sewage to leach into groundwaters, and from there into wells for drinking water, in areas that don’t have municipal sewage systems. If people were getting sick from drinking the water, that would be my guess at the root of the problem.

    Since you mentioned mosquitos, though, that brings up an entirely different problem. Mosquitos breed in water and carry diseases like malaria. Mosquitos can infect you with malaria not because they were breeding in dirty water, but because they bit other people who had malaria. In areas with a malaria problem, the goal is not to clean the water, but to eliminate sitting water.

    Returning to the original question: My understanding is that there is no health issue posed by using greywater (remember, no sewage in greywater!) on edible plants, but that you want to filter the greywater before using it on any plants to make it a little more stable for the sake of the plants. I came to this post in the process of doing some research on this topic, so I’ll follow up with more info as I find it.



    Maybe we need to distinguish how the grey water is used on edible plants? If you spray broccoli with it–or lettuce or have carrots growing in a plot irrigated by the greywater, then your food would be in contact with it directly.

    But if you have greywater underground from a drip hose or mulch pit that is irrigating a raspberry patch or a fruit tree then ideally even fallen fruit never touches the water because the water stays underground or under mulch. . .

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