Home made DIY Grey water system water recycling.

Picture of Home made DIY Grey water system water recycling.
I have always hated flushing clean water down the toilet and wasting the water that goes down the plug hole.

So I decided to make my own grey water recycling system.
It is fairly easy to put together if you are technically minded. And doesnt cost to much compared to other systems.
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Step 1: Basic principle

Picture of Basic principle
The basic principle is when water goes down the plug hole from the bath shower or bathroom sink. It is collected in 2 soil pipes fixed to the side of the house, and then pumped up in to the loft to be stored in a storage tank ready to be used to flush the toilet.

here is a link to a larger image

Step 2: Parts needed

2 x 110mm soil waste pipes.
1 x 40mm waste pipe.
3 x 40mm fitting for 110mm soil pipe
2 x end caps screw on type
1 pump
1 one way valve
1 foam filter
1 storage tank with lid
2 ball cocks
Some 15mm copper or speed fix pipe.
2 magnets
2 reed proximity switches.
2 relays
Some cable

Originally I was going to use a 12 volt pump running from a solar panel. But the pump I had wasnt powerful enough to pump the water up to my loft so I had to use an old central heating pump I have from my old central heating.

Step 3: Assembling the water collection pipes

Picture of Assembling the water collection pipes
To start with I laid out the 2 soil pipes and drilled a hole in the side of both of them at one end so I could fit the 40mm fittings and join the 2 pipes together. And glued in place the 2 40mm fittings.

You will need to make sure there is lots of adhesive on them and they are well sealed because there is quite a lot of pressure in the bottom of the pipes.

Then I drilled another 40mm hole in the top of one of the pipes so I could fit an overflow pipe.

Next I glued the screw on inspection end cap in the end of one of the tubes.

While the adhesive was drying I made up the cut off switch mechanism.
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chrys.clay6 months ago

This may sound a bit cumbersome [ or lazy depending on your pov ] but I use 2 litre transparent lemonade bottles, fill them up from my bath, put them on the garage roof so that the sun kills any bacteria [ google SODIS ] then pour the water into the cistern after flushing. It saves about 55 litres a week on average.

jun_n_venie7 months ago

I am thinking or planning the same project, recycle bath water to flush the toilet. I would need to reroute bathwater pipes and install a new pump and a water tank and reconfigure the toilets to get water from the tank.

Another e-friendly project I'm thinking of is a water-to-water geothermal water heating/air cooling system. Since water is always cold coming in and by harnessing the power of the sun, it could not only save money on gas/electric bills, its e-friendly!

andrewuk2 years ago
How do you protect against the outside pipes freezing?

I'd go with the assumption that this one is built in warm climate. You'd likely have to build it inside if you have actual winter.

(I realize your post was a year ago, but whatever).

avery481 year ago

Really loved this. I am on a well and septic system. We have experienced a rather substantial amount of rain this past year, which has taken us out of a 15 year drought (not a CA style drought). Never the less, we have 5 adults and two small children, lots of bathing, dishes, laundry, etc. Did I say "laundry"? Anyway, with the extensively higher water table, and a septic system installed early in the drought when the soil actually perked, we have water noticeably coming up and flowing on top of the ground during laundry days, it really is the only time it happens. I was contemplating using the grey water for the garden. I think I can adapt your system for that and add the toilet system, serving duo purposes of recycling and conserving fresh water. Thanks you for the inspiration and motivation.

altomic5 years ago
excellent. very excellent. thank you a neat thing that I saw i Japan was when you flushed the toilet there was a tap and sink on the top of the cistern. so you push the button, toilet flushes and water starts running from the tap in to the sink which then goes in to the cistern to flush next time. the sink and cistern were one unit.
iPodGuy altomic5 years ago
That would only put out cold water, no? Not so good for washing with soap and killing germs.
Broom iPodGuy5 years ago
I think you missed an essential point:

The system recycles from the sink to the toilet.

You wouldn't want to wash your hands in recycled greywater.
iPodGuy Broom5 years ago
Yeah, I got that. What altomic was saying is that there's toilets out there with a spout that puts out water for you to wash your hands with. The handwash water then fills the tank of the toilet. That is greywater recycling, but toilets are cold water so all that would come out of the spout is cold. That was really just an observation I made. The system featured in this i'ble is well-thought.
roosta iPodGuy5 years ago
im not sure thats quite right. why couldnt you put hot water into the cistern? the way i read it is that the taps (hot and cold) are on top of the cistern pumping fresh water through fromt the mains. flush the toilet, cistern empties, turn on the tap(s) and the waste water from washing fills the cistern. obviously if you just swapped out your toilet for one of these you would only have a cold water pipe there, but you dont need the old sink either so you may as well put the new toilet where the sink was and then you would have both hot and cold pipes present. then again pipes can easily be moved using flexible piping. i dont know how old this product is by i had a similar idea when i was 14 (2004-2005 time) where the bass and seat of the toilet slid out from under the cistern, and the sink was mounted on top. we were trying to fit a toilet and sink in an under stairs cupboard, but there wasnt enough space.
its actually a lot harder to move the toilet than it is to move the sink. i'd rather move the sink pipes to above the toilet than the toilet to under the sink pipes.
While cold water isn't the most comfortable to wash with, it isn't less hygienic. When my son was learning to wash his hands, even lukewarm water was "TOO HOT!". While complaining about this to a microbiologist friend he told me that the temperature of the water doesn't matter, it's that you work up a good lather to remove the germs. Washing in temperatures hot enough to actually kill or harm the bacteria would hurt! : )
oops, sorry, missed the above post!
no... you will plumb it like a regular sink. i was going to build a fiberglass sink-shower-toilet combo unit for a while but decided to do whole house gray water system and use the excess for the garden to supplement my rainwater system.
madanna iPodGuy5 years ago
Hi. You don't need hot water for killing germs. All you need are wet hands, soap and friction (rubbing the surfaces of your hands together) - thorough drying is also essential. Not using hot water to wash your hands might be more energy/resource beneficial than re-plumbing your toilet. Neat instructable though.
danm95 altomic5 years ago
stinks if you still have soap on your hands when the tank is full! :-P
tanks have an overflow tube... excess water just goes down the tube into the bowl and sewer.
In the US they sell a special toilet top, connected to the toilet water inlet valve, which lets you wash your hands over the toilet tank (not bowl). So washing your hands fills the toilet tank for the next flush. But these are hard to find. Not sold in stores.
johnrclarke2 years ago
Hi - I built a similar system using a massive Magnum Water barrel for storage some years addition to re-using the grey water in the house this gave me the option during the summer months to water the garden/lawn in times of draught. I never cured the smelly filtered water though and we had two toilets that were using the recycled water...eventually my wife banned the capture of water during the hot months. I guess commercial systems must have some complex biofiltration methods to get rid of all that hair,skin and smells generated. Good project though, well done...john
fjpalacios14 years ago
I've seen this before on a renovation TV show, I just never had the motivation. However, after reading through your plans, I'm going to start working on it. Thanks for the motivation!
niallosull4 years ago
hello, maybe a silly question but i live in a bunglow and the waste pipe is just 4inchs above ground level. will this system work or is it only for 2 storie buildings?
Ronyon4 years ago
Very inspiring,what you did here.I keep comeing back here to look at your design. Im wondering how the storage tank is doing.I came across the idea of using aquarium style UV lights to sterilze laundry. I wonder if this would work for keepingb the tank free of dangerous organisms.
dagdon5 years ago
This is a VERY environmental project.  Typically, this will save about half of your domestic water consumption.  Depending on your household demographics and their flushing and bathing/showering habits.  Modern toilets use only a fraction of the water per flush, compared to a couple generations ago.  If you need more "grey" water to balance the equation, consider the output from the laundry, too.
Board of health-wise.  You must have it constructed so there is an overflow of excess grey water into the drain( you have that).  Also, you need provision for freshwater feed to makeup any shortage of grey water.  (If not enough showers, you still need to flush.)  Finally, to pass engineering standards, you must provide for air-breaker and one-way valves so that even if the fresh water system (city water mains, whatever, experienced a momentary suction instead of pressure; the grey water could never enter the freshwater system. 
Congratulations on a very eco project. Nicely done.!!!
BTW, the cabin version of this is the bucket under the sink--bucket used to flush the toilet.
simon72post (author) 5 years ago
I did think about doing it that way. but its good to have a storage tank in case. the toilet is used more. and the tubes outside get emptied. or if I have any problems with the system. a storage tank gives me a bit more lee way.
dkstruska5 years ago
Couldn't you just skip the attic tank and have the pump piped directly to the toilet? A small pressure tank and pressure switch would be necessary, but there would be no exposed water inside to stink up the place except in the toilet.
look at the dps system

Ive seen it, looks good - you should disinfect - legonaires - aerosols - its in the regulations apparently
wazzup1055 years ago
I really like the vertical pipe storage system... saves me from storing a large box full of water... I could just mount some pipes on the wall with an overflow "mechanism" to store some rain water...
Cool project! It's good to see people getting their hands dirty with the whole greywater concept. It truly is a super tangible way for people to start conserving water and make a noticeable difference. For more ideas check out It's a really cool community where people can share ideas and their vision for the future of water harvesting.
Thanks for sharing... that's amazing... As soon as I have my own house I'll try it.
nsgrossman5 years ago
So question: Would this be useful for me if I have a septic tank & well water? This makes perfect sense in a city where filtering requires many resources, but in my current setup waste water goes into my septic tank where it drips into the aquifer and is eventually reclaimed by the well. It would seem the pump needed to move the gray water would probably use a similar amount of power as my well pump, leaving the filtering action as the only real difference. Thanks for the info, GREAT tutorial! Peace Nate
stormuk5 years ago
Simon, Great instructable and it's something I really want to do. Where I've had problems is sourcing a cheap removable/cleanable filter. You mention that you've used a 'foam filter' - can you let me know where I could get something like that and how much they cost? If anyone knows of any alternative filter types that would work for this, that would be helpful too!! Many thanks. James
simon72post (author)  stormuk5 years ago
Hi the filter I'm using at the moment is a foam air filter. the type you would use for a car or motorbike. it will catch most of the larger lumps and hair and so on. it also dose not restrict the water flow to much. it is shaped like a cone. so it dosn't restric the water to much
Great instructable! Where you live does it get below freezing? As I would worry about your collection pipe becoming solid in winter and spilling it's 'precious cargo' :) I think you are on the right track and with a few tweaks and alterations dealing with fungal growth and stagnation, and a few years, some form of this type of system will be legislated in all new builds. Keep it up!
Simon, Thanks for your reply. So you mean like a K and N air filter? Sounds good. rying not to sound stupid now, how have you housed it and connected the pipes to it? I don't suppose you have any photos or drawings of this part? Thanks James
brokengun5 years ago
This is pretty sweet. I haven't seen many DIY grey water recycling systems, this is a good way to do it though. Do you have any calculations as to how much money this will save? I have a well so I have no idea of the cost of public water. What would the payoff be for something like this? Considering your use of an old pump and just some pvc, I bet you don't have much invested...
bbsux5 years ago
I've been thinking of doing this with collected rain water, this may be a big help..
iPodGuy bbsux5 years ago
I would love to try that as well, but it isn't allowed in our town and they monitor our sewage vs. consumption.
I'm confused. If they charge you drain fees based on the amount of water you pull through the water meter, how would the ratio of those change? Other than losses for evaporation (or what might get absorbed into the towel when you dry things off), you are bringing the same amount of water into the house as you are putting down the drain. You are just -reusing some of the water a second time before you flush it down the drain.
n3rrd noamparn5 years ago
If using gray water, there should be little to no discrepancy, as you have stated. bbsux originally mentioned using collected rain water, which would flow through the same sewage pipe, but wouldn't be counted as entering. This would cause a discrepancy if the sewage pipe is in fact metered.
simon72post (author)  iPodGuy5 years ago
Hi you said about your water usage compared with your sewage. That will not change. because at some point it will all go back to the drain. it just gets used twice instead of once. the only thing that would effect the balance of your water usage and sewage. is if you used it for something like watering your garden, where it wouldn't get back to your drain.
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