50 Shades Of Gray Water Reuse


Entered into this year’s Hackaday Prize, [TVMiller] built a super cheap Arduino powered gray water recovery system.

The system is very simple and can be easily made for almost any bathroom. By making a zig-zag of PVC pipe underneath the sink, he’s created a simple grey water reservoir sized for his toilet’s flushing capability.  And if you use too much water, it just backs into the drain — think of it as a giant P-Trap! A 12V solenoid and 240L/h water pump switch on after the toilet has been flushed — refilling the tank with reused gray water! He’s also added an Arduino and an LCD screen to keep track of the water saved; with the nice touch of a HaD logo of course.

We love [TVMiller’s] project brief build logs — he doesn’t hold anything back.

Pipes were glued, the inhaled toxins coursing through my lungs and penetrating the cells, turning me in an enhanced human, now capable of lifting small things with great ease, like a stapler or Big Gulp.

And if you wanna skip a step altogether — why not combine your toilet and sink into one? No electronics necessary!

The 2015 Hackaday Prize is sponsored by:

54 thoughts on “50 Shades Of Gray Water Reuse

    1. While there IS a mesh filter at the top of the T to prevent larger particles, most debris would not be a problem to the system. So what if face pubes get in the toilet. You put far worse in there.

      1. It is not just particles that cog drains, body grease, gels from tooth paste, soap etc all tend to stick to the sides of the pipe. The long winding tubes will make cogging more likely in the long run as you are providing a lot of surface area. It also going to be messy to clean that up.

        1. The higher velocity flow rate (than simply a large reservoir) and consistency (read Everybody Poops) would discourage debris from staying put for too long. It would not likely be an issue for a long period of time. When is the last time you had to pull your PTrap to clear it? Exactly. Wait for it…you’re plumb, out of excuses.

          1. Actually had to do it twice since I moved in. In the last couple of years, I already used up 2 bottles of draino. Chance are that I’ll have to clean it up again in the next few months. If my drains get really bad, at least the trap is removable and worse case is that I can call up the super and he can use the snake to clean up the rest of the pipe. What that all glue down intestine with so many tight turns, it is going to be an issue to clean it up.

            Not sure what your problems with the high and mighty than everyone else attitude.

          2. I end having to clean out the trap in my master bathroom about every 6 months. Usually just Draino or similar is enough. If I don’t do it the drain slows to crawl.

          3. “High and Mighty”? While yes I do feel that way but no, it wasn’t meant to be implied in my reply. I was merely stating that cleaning a trap is not nearly as common (I have been a plumber for 8+ years). Clearing interior pipes is a whole other subject and side note, Drano is trash. If you have old pipes, scarring collects debris, BUT vanity sinks needing to be snaked frequently, unless you have a nearly bald wife, some thing else is wrong. Old pipes and buildings often times have terrible or blocked venting (cleared a bird nest out a couple times) which can be confused as poor drainage. Any who, for a vanity sink, the screen would be more often need clearing than any other collected materials which would frequently wash out.

          1. For the person drinking from the toilet tank? It’s grey water, it’s used…for your poop. I mean, I may have seen a web site that reuses used fluids but…but that’s…that’s not right…for this forum. Not that I would know any thing about that.

  1. just wash your hands in the tank and then flush – lol

    dirtiest water is often the start of a washing cycle – next steps might be:
    – add a valve at the top and have a delayed opening
    – monitor the water – maybe with a clear section of pipe – shine an IR (or something like that) and read the values for cleanest water to open valve

  2. The “combining the toilet and sink into one” phrase gave me a quite a different, and rather sophomoric image compared to what is actually behind that link.

    The things that actually *are* behind that link turned up not too long ago on Ask This Old House, so that means it’s officially a thing now.

  3. I like the Idea, although I would probably have opted to go with a larger diameter for the reservoir to increase the capacity. A simple u of 3″ pipe would fit under many an under-sink cabinet. That said, his design would be nice for free floating sinks with the addition of a simple front panel to hide the pipes. Hacks don’t have to look like hacks. They can be made pretty.

    1. For its appearance, this was more or less a prototype, and he’s very sensitive about how he looks. As to system, original it was meant for a cabinet sink and thus meant to be compact and flexible. The volume was based again on being compact for an under sink space. Now I have to console my ugly machine. It’s all right sweetie, he meant you look experienced.

      1. I apologize profusely. I meant no disparagement. And yes, you look very experienced.

        As for the tubing diameter, I’d have to do the math, but I think you could gain a ton of capacity with little extra space used by stepping up a size or two. And I didn’t mean to make it sound ugly, but this is a system in a room that is often considered to be in need of prettying up already. A simple panel to hide the tubing would be more than enough. You could use it to draw attention to the display even more…..

        1. In reality, it’s hideous like this and that is more or less because I’m poor. Also lazy. Poor and lazy. I’m more see if some thing works and let others John Ive’s the thing. A bigger tube would increase cap but you really have to measure how much sink water is actually dispensed and for THIS sink its really not much at all so a bigger tube is not completely necessary for this particular sink. A flat panel tank would be better.

  4. Tape, very ugly.
    The tap is into the sewer side of the P trap. When it is pumped dry, sewer gas will vent into the system, toilet and bathroom!
    I would not like to smell anything coming out of a ready to use stool, mainly that horrible mint that nobody puts in candy just tooth-soap.
    Hands free with a spray not aerator is saving water and adding convenience. It’s stupid that handwashing fails at the point that you have to touch handles. It only takes a foot lever and the faucets could have been hidden undersink decades ago. No ‘duino needed.

    1. Excellent point about the sewage gas! I had considered that but weighed the options of not giving a shit in this particular example to move forward but you are g/d correct sir!

    1. If you mean the tube, I’d wager that based on the frequency of use, it’s unlikely. Most toilets in a family home are used so frequently (pee, then pee and poo, per person per day) that stagnant enough water for collection is a low probability.

  5. I have no doubt that in this group you will come up with viable options for bacteria issues, micro-solids, etc. If nothing else, this sounds like an interesting idea for off-grid living. Who knows, with some of those issues resolved California may want to talk to you.

    1. And being that I live in California, I’d tell California that I don’t think it’s mature enough to talk to and send California to it’s room to think about the shit it’s done. Bad California, bad. You see that ocean over there, California? You can drink from it, not spill oil and sewage in it. Oh California, you filthy whore.

    1. I’d accept no less than 1.4 in small unmarked bills. Noon tomorrow in a brown duffle bag. That IS how Kickstarter pays you out right? Thanks for the compliment.

  6. As other mentioned, you need to get some degree of treatment. If not, your p-pipe will be teeming with bugs.

    The British Standard BS8525-1:2010 (Greywater Systems Code of Practice) will tell you that greywater should only be for toilet flushing, garden use and washing machines, as long as it has been treated enough. It shouldn’t be used for bathing, dish washing or anything that needs safe and wholesome water quality, because of potential higher health risks.

    You can find that on the anglianwater website.

    1. The water is literally coming from the sink, to the toilet. The only interference is your hands, soap, tooth paste, spit, jizz…I don’t see the conflict with “bugs”. Are you guys watching a different video than me?

    1. Getting a tank under a bath is a serious remodel and the volume of bath water would be far greater than a toilet so bath water is better to be reused for gardening or pouring in to a neighbor’s car when he pisses you off. Using ALL sink water for some thing else is a contribution. It’s not about how much you use in the sink, it’s about how much of that you use can we reuse.

  7. would a small ozone generator bubbling into the bottom of this setup have the potential to remove enough of the bacteria etc. to prevent issues? I’m just spit balling I guess, but it (the existing project) seems like an interesting idea!

    1. Water from source is treated with chemicals any ways (in the US) AND the flow rate is not going to allow for a placid enough environment for issues to arise at any different of a rate than what occurs in the average P-Trap w/o this addition. Aside from that, it’s water to the toilet. Where is all this bacteria concern coming from?!

  8. I’ve thought of this many times, last time was yesterday night, and i havent seen this post yet.

    Well for someone who works daily and is at home only a few hours a day, most of them sleeping i can guess you waste more water on the kitchen, making dinner washing your hands or something, than in the bathroom sink.

    Specially if you talk to a woman she will tell you what are the racio bathroom sink/ kitchen sink, and yes in the kitchen produces more dirty water with solid particles.

    As i doubt the wc sink usage per day is enough to fill in completly a toilet tank, well or you are a crazy hands clean or… that system is a litlle bit useless/ cost over savings, and im not consider your smal tubing reservoir.. (plus it’s problems..)

    Let’s get to the business, my thought was to reuse not the sink waste water, but shower’s one. I bet with only one bath you could fill your toilet 2 times or more, now take into account how many people live in, and how many showers a day..
    For this idea im not thinking of pvc pipes as reservoir, but a big enought tank, maybe 50liters or more. Of couse something this big you cant put it there and hope no ones notice it, in small bathrooms you even dont have space, but with a little engineer, on the back or under the bath tube you could hide a big reservoir, i would add a easy small opening on top just to add some chemical from month to month to prevent most bacteria. And you could redirect hand wash water there also..

    You could do many more things like a system (lever) to send water directly to the sewer instead of tank, to reduce dirty waters but thats not the main point.

  9. Well, everything has to start somewhere, and it is a nice attempt. Overtime the problems will show up, but it is easy to remove so wont be a big issue when the time comes.

    Comments about the volume of basin water are valid. Except for commercial high volume facilities, hand basins don’t produce much water at all. It is also the dirtiest source of graywater in the house (graywater being showers, tubs, laundry and hand basins / lavatories).

    We recommend graywater systems avoid reusing basin water because of the water quality and also the value of this water as additional drain flushing power to help flush the kitchen and commode solid wastes if other graywater is used for irrigation etc (where the real savings can be made in drier climates).

    I applaud the hack for trying, and the use of some automation. About 5 years ago we started with arduino, tried out netmf, and settled on android / ioio for a complete automated solution for graywater, rainwater, condensate and potable water irrigation. It’s now being specified as mandatory in numerous housing developments.

    Haven’t mentioned it on hackaday before because it is now in the commercial world, no longer in the hacking realm. But if you want to see what the finished products look like, go to waterrenu (dot) com

  10. Nobody seems to have mentioned the high likelyhood that something in the waste sink water will eventually prevent the flush mechanise from sealing correctly, resulting in a leak and wasted water. I think this might only apply to newer cisterns.

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