We have just built ourselves an outdoor kitchen next to our veggie patch which we can't wait to start using.. We are now setting up a simple grey water system to collect the water from washing dishes to use on the garden. We have done a lot of research - but we have never used grey water or built a system like this before so I thought I'd run my idea past those of you who have experience with this before going ahead with it to see if you guy's have any tips or things you would change about it or if you think it might just work fine..
Beneath the sink there will be a 30lt plastic bin with a small pipe leading the grey water directly from the sink into a hole in the lid of the bin - which is elevated.
The water will then pass through a piece of cloth which will catch any excess food waste.
The cloth is attached to a plastic sieve bowl which is layered with scotchbrite at the bottom to catch any other little food bits / oils
the water will pass through the scotchbrite, the sieve and then into the layers of thin sand - charcoal and lastly larger stones and finally out of the filtration system at the bottom and into a new bucket which we will attach to our irrigation system to irrigate the plants from soil level (have read that I should avoid splashing grey water onto leaves)
p.s. We need to try and re-use water whenever possible as water is very scarce and of bad quality on the island - shipped over from Athens by boat - by next year we hope to collect rain water to help with this
We are also thinking to create another water filtration system to filtrate the tap water before irrigating other parts of the garden as our tap water is of poorer quality during summer months and becomes very salty - so any ideas on that would also be welcomed
We are considering a thick layer of compost as an additional filter right at the very end of the system. what do you think?
Hi Emma! Sounds like your filter plan certainly goes above and beyond the call of duty. Grey water garden irrigation is a great way to reuse water. It sounds like you've put a lot of thought into this and have concerns about the water quality being used for garden irrigation, which leads me to believe you may garden using organic methods. I think the only real concern may be the soap/detergent used for cleaning said dishes, unless the water being brought over by boat is of questionable quality. Phosphates in detergents can sometimes be not so environmentally friendly. I imagine if you're using non chemical soaps, you're going to be just fine. All those food bits being caught by the different layers of traps in the drain can certainly benefit your garden soil. Pitch those scraps in the compost pile, or if you don't actively compost, dig a small hole in the garden, dump scraps in, cover up. Let them decay there in the garden providing organic matter back to your soil.
Microbes living in the soil have some amazing abilities to break down chemicals and crap, not to mention the everyday role they play in soil health with breaking down organic matter and converting nutrients into forms available for plant roots to uptake. You can inoculate your garden with beneficial microbes to aide in these processes. Your idea if adding a thick layer of compost at the end of the system is a very good idea, and I would not limit it to the end of the system. Add compost everywhere in the garden if you have it available, provided it is quality compost, smelling clean and earthy. Hope this helps!
"Study books and observe nature; if they do not agree, throw away the books." ~ William A. Albrecht
Be aware that greywater stored in a tank for more than a few hours will turn to black water. There may be simpler designs which will be more effective than the one you have devised. Using greywater in a piped irrigation system is fraught with peril.
Thank you both for your replies!
James - yes well, we are total beginners, experimenting and learning as we read / try things out and talk to other local organic farmers. we have been trying various methods of making our own compost - all going well, but very slowly so we are yet to use any of it on the garden. we also have a compost toilet just recently made up - so we will eventually be composting all over the place!
we have tried out the grey water system as we wrote out above and so far so good - the water comes out clean, it takes time to filter through the layers - which for some reason gives me extra piece of mind..,
We are using our own home made potassium based soap - our soil could do with more KOH and we defiantly do not need anymore sodium - which is in most eco soaps and already in high amounts in our tap water
Tyler - yes we did have a look at this page and I too am worried about using the grey water in drip irrigation, but I am hopeful that if we keep a good eye on our system (everything is very accessible and removable) we can avoid overly dirty grey water from getting into the pipes maybe.. we are thinking of adding a second bin to the system which will have a second round of filtrating before the water goes through the drip irrigation system. I can't think of any other system that would allow us to re-use the water without spraying over the veggies, any ideas?? The sun here is so hot that water when sprinkled from above doesn't really reach the roots much..
Another thing to mention - we were also thinking of running extra tap water through the system so that the tap water comes through a little better quality for the plants, as the grey water won't be enough to feed all plant's this can also flush through to top them up a bit..
We need a lot of water to water all our veggies and it barley ever rains here ;( - so grey water has no chance of sitting around for more than a few hours as it will be used on the same day
The most successful system advocated is to use the greywater for shrubs and trees. It is piped to the trees with a system of biggish diameter pipes which resist clogging. The trees are next to mulch pits into which the water flows.
Hey Emma! Be careful letting too much potassium hydroxide soap get into your soil. It's is very caustic on the alkaline side and can rapidly alter soil pH's, bringing them above the neutral threshold. Some plants prefer to grow in alkaline soils like Clematis, Geranium and Poppy but most, including our food crops, like a pH around 6.2 - 6.5, sometimes even as high as 6.8. Exceptions are plants such as blueberries, they like a soil pH around 4.8 - 5.5, depending on cultivar. Just be mindful of the soap, and if your garden starts looking real bad, check the pH of the soil, as that may likely be the cause.
"Study books and observe nature; if they do not agree, throw away the books." ~ William A. Albrecht
I have the graywater from my sink running directly to a large (6") black corrugated pipe that I cut slices in with an angle grinder. Its about 20' long buried maybe a foot down. It runs along the hill side above my garden, I figured the water will all filter downhill to the garden beds. My land is a continuous gentle slope.
The only thing I do different with my dishes and such, is I am careful to not put grease down the drain; For instance I usually put a half cup of water in the skillet after I cook meat and simmer it then I pour that over my dog's food in the morning. The Dog likes it, and its less grease when I wash the pan.
I will say that my soil is very sandy, everything drains well.
Be Content. And work for more time, not money. Money is inconsequential.
I agree with James, you may be going above and beyond the call of duty!
I use a 15 litre container under the sink, and carry it out to water the herbs and vegetables in the kitchen garden/greenhouse that is right outside the door. I've been doing this for about 15 or 20 years and the soil seems to love it. I use soap and detergent but very little, partly because I want to use minimal water because I have to bring it by hand, and partly because it's going to the garden soil. Things like the daily coffee cup or a plate used for bread (non-greasy) I tend to just wipe and rinse with a warm clean sponge and rinse, and save soap or detergent for greasy or dirtier things. I mulch the garden with about 2 to 4 inches (5 - 10 cm) of mulch. I am careful to pour the water onto the mulch, not leaves, and not to splash the dirty water on vegetables. Sure there's a little oil and soap in there, but the mulch and soil seem to digest it all nicely (I don't discard cups of oil or butter into my sink, and preclean a greasy pan with a piece of paper that goes into the compost). My garden, like all gardens in the region, has a raised line of earth around each garden bed, so I fill up one sunken area with water, and then move on to the next one. For salad plants that I will be eating raw like arugula, lettuce, and herbs, I don't water with greywater, and only water with clean water.
I am afraid that your drip will clog anyway after some time, even though you've got all this filtration, because drip systems often clog even with a "clean" water source. I believe it's better (and simpler) to have less-filtered greywater go into a hose that goes out to the mulch basins or garden beds where it's needed, and then move the end of the hose to a different spot daily or as needed. You can use a screen under the sink before the water enters the container that has the hose attached, and then empty that screen daily or when needed, but sand and charcoal filters are really unnecessary. How are you going to clean the sand or charcoal when it gets clogged? Ugh!
If it were mine, I'd pipe a hose out of the bottom of the 30 litre tank under the sink, directly to the garden, such that the hose can be moved to different sections of garden. The tank would serve to moderate surges, and to mix / cool down hot water before it goes out. A hose to the garden would be a convenient improvement on my current "container under the sink" system.
Works at a residential alternative high school in the Himalayas SECMOL.org . "Back home" is Cape Cod, E Coast USA.