I recently saw an episode of "peak moment" on the internet about a family who built a load bearing cob house with a living roof, a composting toilet, and a gray water system. She mentions that they use worms to filter the gray water and that it works really well. I was wondering if anyone knows any more about how to do that. I'm not sure how it would work. Perhaps having the gray water disperse through a pvc pipe with holes drilled in it but buried in a layer of gravel with soil and compost on top that you introduce red wrigglers to? Any thoughts or other ideas?
What were they using this water for? Were they trying to drink it again? These are just the opinions of someone with little grey water experience, but for what that is worth it seems like the soil would do a fine job of 'filtering' grey water. It seems like filtering or cleaning it is redundant if you are going to use it for irrigation.
posted 7 years ago
No they did not want to drink the gray water.
They used some kind of filter involving worms (like red wrigglers) to eat the food particles from the dish water. You can't just dump gray water straight into the ground. I mean you can, but it's better to have some kind of filter first, I've read about many types of filters that all sound annoying and high maintenance, but these people just used worms to eat the food particles and then they could use their gray water to water vegetable gardens, whereas normally gray water is not used on edible gardens. You could just dump the gray water straight into the ground if you had some kind of septic field, but I don't want to have to dig or bury piping, or buy gravel for drainage. I would rather use a filter and then send the gray water to a holding tank to use for watering the gardens. The great thing about the worm filter was that the gray water was cleaned by the worms and they were able to harvest worm castings from the worms.
Sorry if this is off topic, but I am having trouble finding this information elsewhere. I noticed that the pdf says not to use grey water on your veggies but it is fine for fruittrees. Why the difference? It seems that the processes both use to uptake nutrients from water and the soil to produce edible parts would be the same. What am I missing here? I was also under the impression that many earthship homes used gray water for their veggies.
posted 7 years ago
I was surprised to see that it says not to use on veggies or anything but fruit trees, but I think for one thing it's probably to cover their own ass, to make sure no one gets sick or anything, and number 2, it could be due to soap detergents in the gray water? The soap is the only thing I can think of that would be a problem for the veggies since soaps have lots of phosphates and could have other chemicals depending on what you use.
posted 7 years ago
True, but it seems the worms are there to eat the food particles. I don't think worms would be able to help with phosphates or triclosan or whatever else may be present in detergents. I think that would be taken care of by the bacterial action of the soil in your yard/garden.
They say that the phosphates aren't the problem, it's the sodium that is in the soap too. Also, the food particles if applied directly to the top soil would cause mold (that's my opinion not on the site). Grease is supposed to be an issue when applying directly to the soil/plants, which is why most gray water systems use some sort of filter to trap grease before applying to anything. This website says that the main reason to avoid using on veggies is just in case any sort of disease causing pathogens are existing in the water and that they don't transfer through to the food. They do say that if you have to use graywater on your veggies to only use it on plants like corn, tomatoes, broccoli, or anything that doesn't grow underground (like potatoes or carrots) or lettuces. They specifically say not to use it on greens, or anything that could get the water directly on the edible part of the vegetable.
Anyone considering using graywater for gardens who hasn't before should check it out, it seems to be an informative website.
These folks make and sell black water systems that work with worms. Apparently, they have installed them successfully, in alpine areas, arid areas, sub-tropics, and tropics.
One can go away for a while, system slows down, and then when one returns, the worm eggs left in the system will hatch and back to poop fest.
http://www.wormfarm.com.au/domestic/ PRI's website had a nice write-up on them a while back, you could search there for the article.
A lot of things come out of nowhere, so look everywhere.
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