Greywater Precautions

Before we continue our greywater series, we have a few precautions to lay down. The dangers of greywater have been exaggerated in the past and it’s important to remember that nobody in the US has ever gotten sick from exposure to greywater. The plumbing codes in this country are overly cautious in their restrictions on greywater use, as the Man, quite simply, wants you to throw perfectly good water down the sewer. On the other hand, a lot of hippie types have been a little too loose with greywater and nasty bugs like e-coli, pictured on the right, remind us we need to be careful. So here are SurviveLA’s rules to follow when using greywater:

  • Do not apply greywater to crops that you will eat raw, such as strawberries, carrots or lettuce. Using greywater on any vegetables is somewhat dodgy in general for heath reasons, but greywater is fine for edible plants such as fruit trees where the crop is far from the ground and the risk of direct contamination by contact with contaminated water is low.
  • Do not apply greywater to lawns (lawns are evil anyways) or to the foliage of any plant as this can cause a microorganism growth party. Remember that greywater is treated by moving through soil.
  • Greywater tends to be alkaline, so avoid using greywater on acid loving plants such as citrus, ferns and other forest plants (pretty much anything that grows in the shade).
  • Occasionally irrigate your plants with fresh water to prevent the buildup of salts from soaps and detergents.
  • Do not distribute greywater with a sprinkler as you don’t want the potential bad stuff becoming airborne.
  • Do not use the water from your washing machine if you are washing diapers (gross!).
  • Do not allow greywater to stand as it will quickly become the perfect habitat for anaerobic bacteria which will quickly turn it into a stinky, mosquito and fly infested pool of blackwater. Plan a system that will, ideally, use your greywater immediately.
  • Use only detergents and soaps designed for greywater systems such as Oasis Biocompatible Cleaning Products.

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  1. I realize this blog is rather old – about 4 years – but if anyone who knows about greywater is answering this, I do have a question.

    Presently I staying in a home where the owner requires that water from washing dishes be stored in large plastic containers and then used to flush the toilet. My concern is with the food particles that ends up in the water, standing in the bathroom and kitchen waiting to be used. Even in the sink dirty water stays in the washing basin throughout the day. Many of the plastic containers also are soiled with some sort of black goop and often the water, even if left for the day seems to have a scum on the top. When pouring this water into the toilet, after it flushes itself, the remaining water in the toilet is often left with floating food particles. So, as far as I am concerned this doesn’t seem healthy, but I’m wondering what the experts would say.
    Thanks. Sora

  2. Wow, Sora, where do you live? That’s pretty intense.

    Sink water is technically black water, not grey water. Generally folks who do greywater do not save their sink water. Food particles in water start to rot and smell very quickly (as I’m sure you know), and a bucket of old sink water can grow some pretty interesting bacteria pretty darn fast. This is why, along with toilet water, it is classified as black water.

    If the water went *immediately* from the sink down the toilet, that would be one thing–no time for rot to set in– but it’s the sitting around that makes Erik and I raise our eyebrows.

    It’s just a very unpleasant idea–there must be bad smells. We aren’t expert enough to speak to the safety of it, but I’d imagine if you got some old sink water on your hands, then forgot to wash them, then ate something, you might get sick.

    Generally speaking in greywater conservation we believe in doing the easiest things first. Washer water is super easy. Bath and shower water is easy. Sink water is extreme, and must be done very carefully if at all. It has to be treated with lots of care, not casually.

    I know if your landlord requires it, you can’t do anything about it. To your landlord I’d say it’s fantastic to want to save water, but when it comes to the sink, I’d try to wash dishes with as little water as possible (and use as few dishes as possible) and just let the dirty water go. There’s a lot of resources for low water dish washing.

    If that’s not satisfactory, then it would be smart to hit the books and find safer, cleaner ways to deal with your blackwater. Check out the writings of Art Ludwig, greywater guru.

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