Our criteria for building the greywater system for the tinyhouse was pretty simple: cheap, made from readily available materials, and effective. We also wanted to use the outputs to irrigate a grove of important fruit trees, as water is very precious here, especially in a dry year.
After many, many hours of research on systems involving reed beds, infiltration trenches, fancy UV zappers and all the rest, we decided, on the advice of permaculture and greywater specialist Ross Mars, to keep it simple, and let the biology do the work.
To summarise the approach (and Ross Mars’ general take of domestic greywater), we decided that the intermittent trickle of water coming from our bath and shower would be best dealt with in a living and dynamic system, rather than in a series of reed beds or trenches.
I should note here that our greywater output is coming from just our bath and shower, so it contains water, a little soap, and the inevitable bits that come off a human when they wash. All the kitchen water is processed via a different system appropriate for blackwater, which i’ll explain some other time.
Reed beds in action – great for some scenarios, but maybe not for ours.
Diagram of a typical domestic grey water reedbed system
We had expected to take the reed-bed route, and pass the greywater through a series of gravel-filled reed beds to clean it up before irrigating the fruit trees with the output. However, Ross mentioned a good point.
Reed beds need to be cleaned out every 5 years or so, as they do clog up with biological material. And of course you don’t want them to overflow with raw greywater into an area not designed to take it, as that would defeat the purpose.
Incase you’ve not have the opportunity to dig out a gravel pit full of reeds and their remarkably extensive root systems, let me summarise the experience – it’s hard and dirty work, and it takes ages. And then you have to wash the gunk off all the gravel, and put it all back again.
Henceforth, the periodic ‘cleaning out the reedbeds’ is usually one of those things on the to-do list that doesn’t get done when it should. Which in turn means many a reed bed greywater system that works great for the first 5 years, and then poorly after that.
What Ross suggested was a very simple system. Super simple, even. And he has just finished conclusive research to show that it does definitely provide as good an outcome as any reedbed system, as far as health and safety goes. But with far less overall energy inputs.
The basic structure of this system is a settling tank, followed by a surge tank, which feeds to a dripline under mulch, to water forest garden plantings.
For our settling tank we used a plastic IBC, and built it a concrete surround. The tank has an inspection hatch at the top , and will need to be cleaned out once a year with a siphon pump to prevent sediment build-up
When this tank is over 3/4 full, it overflows to the surge tank. The water in the surge tank then drains to the dripper system. In this way, the drippers get intermittent watering.
The placement of the inlet and outlet pipes is important in this design. The right angle on the inlet pipe does a lot to dissipate the water’s energy. The way that the raw greywater enters the settling tank pushes the water that has been there longer (and henceforth dropped out most of it’s sediment) further up the tank.
This in turn means that the water overflowing to the surge tank is the water that’s been in the tank for a couple of days already, and therefore is cleaner as it’s particulates have had more time to settle.
The surge tank ensures the water level in the main tank remains fairly constant, which reduces turbulence in the main settling tank, and improves settling.
Once the settling tank is 3/4 full, when a surge comes (ie we empty the bath or have a shower), it overflows to the surge tank through a outlet pipe and onto the driplines around our fruit trees downhill, with the whole system working by gravity.
One of the many beauties of this system is that it doesn’t need any filters as such – there is no filter on the outlet pipe, for example – Ross’s research has shown that designing for fluid dynamics means good sediment settling – which in turn works much better than filters on pipes, and results in a much more overall passive system that is self-regulating. Huzzah.
The fact that the dripline is under mulch is another central point of this system. This way the outgoing greywater is in direct contact with the soil food web (and not with the air, weather and animals) when it gets out into the world.
This in turn means that we’re putting the onus on forest garden soils – a large, stable and distributed ecosystem – to process the greywater in it’s final stage, rather than concentrating the greywater in a pit and relying on the limited (in both space and numbers) biology in there will do the job.
Time to dig a hole for the settling tank, which needed to be below the output of the bathroom
The trough heading down to the future orchard plantings
IBC tank ready to go in
Formwork to keep the poured cement surround in place
Pipes in place – this photo shows the outlet from the settling tank
Inspection/cleaning hatch in place, it’s time to pour the surround
Everyone helped scree the top
And done. pipe outlet to surge tank is on the left, overflow pipe (only relevant in an emergency) is on the right
Our surge tank, a modified olive pickling drum
Completed tanks – inflow from bathroom is the white pipe coming in from the right, outflow to drippers exits out of small black pipe at bottom left
Completed tanks with output pipe to drippers coming out of the surge tank at bottom left – there will soon be a big retaining wall along this cut, sitting on the concrete foundation
Trench for outflow pipe from surge tank, down through the swale and to the future dripper system below
Filled in trench, seen from downside of the swale, ready to be hooked up to a dripline system
The eventual result (sometime soon, once everything grows) – a stable and diverse polyculture that processes the grey water and yields much fruity and herbal goodness
So in short, this system relies on getting the water out into the biological sub-terranean communities of a forest garden as quickly as possible to let biology clean it up and cycle it back through the ecosystem, rather than holding that water and processing in a pit or tank.
In part 2, I’ll explain the octopus and how we’re going about designing the output zone of this system, both in terms of plantings, dripline and all the rest.
Huge and noisy thanks to Ross Mars of Greywaterreuse.com.au for his generosity and good advice in our hour of need. Check out his site for lots of great resources and info about this important factor of sustainable habitats. As Ross says:
Greywater re-use for garden irrigation should be encouraged in both urban and rural households. It utilises a valuable on-site resource, conserves precious drinking water and reduces the load on wastewater disposal systems.
If applied appropriately to gardens, greywater re-use presents minimal health and environmental pollution risks.
The key to appropriate greywater re-use is user-awareness of the issues surrounding greywater. With increased grey water knowledge, permaculturists can play an important role in promoting the sensible re-use of this household ‘waste’ water.
In the settling tank are both the top and bottom ends of the outlet pipe open?
I second the question! Why are those T-shaped rather than just elbows? Thanks for this, I think you just saved us doing a reed-bed system.
The word from Ross: “Main reason is to trap floating oil, grease, debris so it doesn’t pass into pump or surge tank. The sedimentation tank acts to hold both bottom sludge and oily material, and you only draw water from middle of tank into next one. The T piece also enables a shock load to enter first tank so that it doesn’t pass from one tank to next too quickly. “
That still doesn’t answer my question…
Are both the top and bottom ends of the outlet pipe open? The top looks open in the picture. There’s no mention of that detail in the diagram.
yes! Top and bottom of inlet pipe both open, and same for outlet pipe 🙂
Yeah, sorry. I sort of hijacked your question. The T-shape (my question) is so that the top and bottom can be open (your question) which allows the muck to float at the top of the inlet (and outlet) instead of being forced down into the settling tank where it would proceed to float back to the top, and ruin the ‘clear’ middle section.
Kirsten – does this arrangement strike you as almost identical to a septic tank, except for what goes in, and the surge tank?
Thanks!
I’ve been using what my Dad would have called a “half-arsed” (i.e. bodgy) version of this system to process laundry water for many years in my urban food-forest. Biology is best! =)
A tip for cleaning your settling tank (you possibly already know this!) is to use a hose for a swimming pool vacuum to create a syphon. We also use this method to clean out the bottom of our water tanks. If you run it into a holding tank of some kind it makes great fertiliser although I suspect that with a grey water system you might need to compost it for a while.
yep we’ll be siphoning for sure 🙂
why not have a large outlet at the bottom?
I have seen a reed bed filter using a small round water tank cut off so it was about half a meter high. The tank was filled with rocks and reeds. Water came in via a pipe on one side, below the rock level, and out the other.
we are trying to get something similar approved for our house. Council wont allow anything that doesn’t have an EPA approval number, and sadly in Victoria the only approved systems are the high cost, high maintenance, UV zapping, pumped type things. Hoping we can get a biological system that can make use of our water. Very interested to hear what system you have for your kitchen water.
Thanks for this great post. What kind of drip line are you using Kirsten? I’m having trouble finding drip line that will work on my gravity fed rainwater system which has only about 1-2 metres head.
Thanks heaps for this post and detailing why you went with this system, in my ecology courses we learnt that wetlands often move from being fairly open areas of water to dry land over a period of 10 – 200 years (depending on dozens of factors) so when you explained the bit about cleaning the reed beeds out it suddenly clicked. Nice work using the soil food web to do the purification which you would otherwise use the reed beds to do. Very nifty and very permaculture. I have a soft spot for reed beds as I like how they… Read more »
Thanks again for sharing. I just wanted to be clear on what you are trying to achieve by having the 2 tanks. If you are storing the greywater it will no doubt get stinky… I am all for a large surge tank. With the subsurface irrigation that you have set up, I don’t see it as a health issue etc. just an ongoing maintenance issue. I look forward to the area coming alive. Also I cannot tell by the photos but do you have desludging valves at the bottom of both tanks? As always appreciate the work that you are… Read more »
Can you write out a parts needed list for this system as Im going to build it. I have the 1000 tank and the olive barrel. What else is needed please and what size and lengths sizes are the pvc pipes. Thanks for all the great info Cheers
Hi, great article, I’m ploughing through your site with enthusiasm and look forward to implementing many of your ideas in the future.
You mention that you deal with kitchen water as though it is black water; is that because of legislation in Australia? I had hoped to use ‘environmentally safe’ cleaning products such as Ecover and treat all my water as grey; would this work?
I also read your article on mulch pit grey water systems; could this not also be used for you grey water from the tinyhouse?
Looking forward to reading more.
Thanks
Kitchen water is considered black due to the presence of organic materials such as food waste. I suspect that legally you cannot treat black water as grey water. But It may be worth a shot, especially if you have screens over your kitchen sinks drains.
Yep that’s why this system does not process our kitchen water, only our bathroom water
This system is completely overkill for something so simple as bathwater. The “septic/settling” and surge tanks are completely unnecessary. Exactly how much biomass/sediment do you plan to wash off yourselves!? LOL The simple way to handle greywater from showers, tubs and laundry is a branched greywater system piped to mulched basins planted to fruit trees, as explained very well by Art Ludwig at OasisDesign.net in his book ‘Building An Oasis With Greywater’ and can be done at a fraction of the cost that you spent on your “engineered” system.
Hi Paul, if you read back thru our other posts on greywater re-use you’d probably have picked up that we have built previous versions of mulched pig greywater systems similar to the ludwig designs (tho not exactly as it’s really hard to get the branching pipe brackets that he specifies as being an essential part of the system in Aus), but with our soils they just didnt work very well (we just ended up with manky ponds under mulch which didnt drain sufficiently, due to soil type) – nothing works in every context 🙂 – you would be surprised how… Read more »
Dear Kirsten,
Many thanks for this excellent article (in fact your whole website!).
I was planning to follow your example and make myself a greywater system after having given up due to the reed bed requirements m-a-n-y years ago.
But today I read a web page which put me off once again; therefore I’d like to hear your opinion on the problems outlined on this page (especially with regard to storage of greywater): http://oasisdesign.net/greywater/misinfo/index.htm#storage
Have you had trouble with stagnation or is your throughput enough to prevent this?
Many thanks,
Abdullah Eyles,
Ankara, Türkiye
This is really interesting, all the different views and suggestions. I have 4 small design / concept Q’s please; 1. Does the plan include (or not) a lower outlet for cleaning sludge? 2. How would one remove the sludge without removing the standing water above it? 3. Wouldn’t the water stink / stagnate as most of it just sits there. (The outlet is 3/4’s of the way up the holding tank. What shock surges come from the bath?) 4. Since creating this would you change any of the design? My folks live near Budgewoi and they are not allowed to… Read more »
Kirsten,
I can’t get it from the text! Is this a no frost area your are living in?
I actually live in continental Europe(western Romania) with temps like -20 C in the winter.
I suppose you do not have this climate there sin’t it?
Yep we get frosts and get nights of -10c ish?
Kirsten,
thanks for your answer, I meant we really have cold winters with day temps of -20 and lower, and this for weeks sometimes. Nights is of course even colder I
I just wonder if a similar sistem would wor for me as the vegetation is actually dormant for 3 to 4 months. I can’t think of storing the water in a tank for the winter.
Where did you get your IBC from please? Do you remember what it roughly cost?
Was it one that was certified chemical free and leak free?
I asked above; “why we need these systems”… not to be argumentative, but to understand why we shouldn’t just run it straight under the mulch. Under the mulch to ensure it doesn’t touch leaves etc and also so the precious water goes straight to where it’s needed, the soil/root systems. Sorry if the way I asked was considered rude or offensive. It was not meant to be that way.
Thanks.
Hey David, this tote was 2nd hand and previously had diswashing liquid In it… Was about $100 I think… The point of the system is that if you run straight to drippers, there will still be gunk in the water which will clog yr drippers. The whole point of this system is to settle out the gunk so the water entering the dripper system comes out clean enough to ensure the system works long term… The idea being that all the water entering the system reaches the drippers in a day or so. For our climate, soil types and drought… Read more »
Great system. We have a greywater system (or two). One from our washing machine and one from our kitchen. it works great. Very simple design with pvc pipes. We will also be installing another system soon from one of our bathrooms. That is on the back of the house but it will be simple also. One day, i will do a write up and take pictures … 🙂 I encourage people to just do it. It really isn’t rocket science and I love not wasting all that water.
Hi there. The information is absolutely awsome. Question. Is it possible to have an open tank instead of a closed lid? are there issues with smells?
The lid is recommended so that nothing (or no-one) falls in, partly because that would suck as an experience and partly because you dont want the inlets or outlets clogged with dead lizards, or anything else. Plus you want your greywater getting back into a stable biological system (ie the soil) as soon as possible without coming into contact with too many things like flies, insects, etc. The holding tank doesn’t smell bad, but the whole point of it is to let the solids drop out of the water before the water progresses to the drippers, so i assume at… Read more »
Could you have used the drain tap (approx.) 50mm on most IBC to drain the sludge straight out for collection or into a/your blackwater system e.g. biomass digester .
Hi Kirsten,
Love the design!
Two questions,
Is this system a sealed design? ( When water rushes in, air needs to escape. As I see, the only escape is through to the surge tank.)
How is it going 6 yrs on? Would you change anything?
Thanks heaps!
Hi Kirsten. I’ve been wanting to install something like this on my site here in Argentina since I first read this post last year. I’m getting closer to being able to, but wanted to ask how much of a drop you need between the inflow of grey water and the tank? Mine is direct from kitchen sink and washing machine, but my land is totally flat, grrr. Also, you mentioned that you have another system that might be better suited to black water treatment… Are you planning to post on that? (Would love to see it!). Thanks for always being… Read more »
HI Kirsten- We have an old-fashioned septic system on 1.25 acres. I’m now thinking to use the gravitational energy of the pumped effluent through a similar system to yours. Problem is, ours is septic effluent, not grey water. I can’t find much about septic effluent treatment, other than traditional drain field systems. We have a downhill orchard with dripper line already installed, and it seems like a match made in heaven. OK so its black water, but there are two mitigating factors: we plan to start using a dry composting toilet, which will remove some, but not all faecal matter… Read more »
You might look into mushroom bio-filtration. Don’t use the logs that the other poster mentioned, use straw bales and wood chips with the same type of mushrooms (oyster).
This is good for someone who has the space and money and inclination to use cement, buy plastic tanks, etc… Some of us are looking for even simpler, less expensive, solutions that use as many living biological factors as possible, and as little industrial inputs as possible. To make my small (20′ by 5′?) pond I mixed in sodium bentonite about 5 or 6 inches into the native soil/clay. It’s only partially full of water and I already planted water cress, native reeds, duck weed, etc, in anticipation of the winter rains. I am presently digging out a short (5… Read more »
Hey Angus…just read your on Milkwood re. your greywater system & I was wondering where you live & if you have it all working……[email protected]
yeah reedbeds weren’t an option for us to get this system past council due to our system’s proximity to a seasonal creek – glad yours worked though 🙂
Mine is about 40 metres uphill from a watercourse……..the Council inspector calls now & then……no probs.(only two people contributing to system)…want photos…[email protected] (no worries I`m 77 yrs.)
what about making a Biochar treatment system….especially using Bamboo to make the char.
I’m curious how you joined/sealed your PVC to your pickle barrel. I have almost exactly the same barrel that I’ll be using as my gray water settling tank. My surge will be handled by “Infiltrators,” (brand name you might not have down there). These offer a combination of leach and surge at the same time.
I will place the tank on gravel but I want to get a reasonable (perfect is reasonable 😉 ) seal on my inlet and outflow.
I just used poly tank flanges for the poly joins
Why wouldn’t you just flow the water out to the garden directly? Sediment?
Yep partly – removing the guck so the clear water can be distributed to many different trees via drip irrigation, which requires the water to be clean or all the drippers clog up
In 2005 I built a large double stainless steel (from scrap) Clivus Multrum composting toilet & modified it to take both grey & black water……..I also included a worm bed…..the liquid from this goes into a pickle barrel bio filter (with a long stainless steel gauze filter) loaded with different density swimming pool filter foam (it has to percolate from the bottom up) thence into a large teardrop shaped rock & gravel loaded reed bed (4M long) then out to plants………The vermi- compost (which is a sludge & doesn`t smell ) in the CM has to be cleaned out about… Read more »
awesome! we were told reed beds weren’t an option (to get our system past council) b/c we were too close to a waterway – albeit a seasonal creek. glad yours worked though 🙂
Howdy Kirstsen. I’m a Plumber and Gasfitter and the distances are ridiculous. I have a 50 acre’s block and not allowed to build on it because of the 100 meters rubbish. Even a treatment plant is classed as effluent and It is clear as any mains water you can get. Talk about over regulated,we can’t even have hot water in our own homes, it has to be tempered down to 50C. I’m the bearer of bad news in so many ways. And I don’t like the disappointed look,and others it is anger. And my hands are tied. One of my… Read more »
Hey guys – I know this a few years old now but I wanted to follow up and ask how you suggest handling the kitchen sink waste water. Could you just run it through a grease trap and then into the same grey water system described above?
the kitchen sink water we ran into a long shallow gravel pit that we were planning to build a kitchen garden on top of – that never quite happened (the kitchen garden) but there was plenty of grass grown instead 🙂 as we were on tank water, we were conservative with how much water went through that sink, so it wasn’t a problem in terms of overloading…
What do you do if you are going away..to avoid Grey water sitting too long and going bad? I was wondering if a valve at the bottom might have been a useful addition? Also I assume that the size of the tank should be in relation to quantity of Grey water produced to ensure it is not being stored too long. I understand Max of 24hrs is recommended. I think it would be interesting to test sediment deposition with different holding periods. Maybe 1 day is enough?
The diagram of the reed bed system you have there has the grey water flowing directly into the reed beds. The system we’ve had designed for us has the grey water going through a settlement tank before going into the reed beds. That’s the process we needed to go through here in SA. The reeds clean more organic matter out before running onto the fruit trees. And the reeds are slashed annually and will provide mulch for other parts of the garden
Hi Kirsten! Thanks for everything you guys do! seriously every time I google ‘how do I…’ you have the answer there for me! I just have one question which I couldn’t see in the comments below. What are the reasons for concreting the IBC? Does it need insulation? Or is it to keep the sun off so it doesn’t turn green, or something different altogether?!
Thanks m advance!
Thanks, Sarah, It was just so we could bury the IBC and not have it be crushed.
So where is the overflow for the IBC? In one picture you say it’s the pipe on the right, and in another picture you say that pipe is the inlet from the sink. Surely you’d have to have one to stop the plumbing from backing up and flooding the house
I have 35 years of hands-on experinece with these systems and I would certainly not recommend a GW system that puts GW in a tank. The #1 worst thing you could ever do with GW is store it in a tank – it serves absolutely no purpose and will simply make the GW stink. Not to mention the totally unnecessary cost of the tank and installation. Use a coarse filter if you have lots of crap in your GW, but not a settling tank. An efficient GW system does not need to be this complicated. Get the GW out of… Read more »
thanks grand – yeah we have moved on from this system (bc we moved on from the property) but the idea with this, as we were told by various greywater experts, was more to settle the sediment before it went to drippers under head than to store the greywater… so yes as you say, storage of greywater is not the main game here, just to settle the crud out before it headed to drippers
Do you have a link to your black water/kitchen water system?
I don’t see how this system removes dissolved soap, shampoo, toothpaste, shower gel, deodorant, with all of their chemicals. I see that it lets the solids settle out to get rid of human skin, hair, and other coagulated material that is more dense than water, but the human body fat, chemicals and detergents remain and are passed untreated to the soil? In a reed bed those chemicals are to some extent treated by the plants absorbing and breaking them down. Have I missed something?