The Countdown to Maker Faire Bay Area is On!


Build This Water-Saving Toilet Tank Sink

Furniture & Lighting Home
Build This Water-Saving Toilet Tank Sink


Jon-A-Tron from Instructables has posted a project on how to build a toilet tank sink. I’ve been thinking about adding one of these to my bathroom and this certainly makes DIY look very doable.

Jon writes about the project:

Why use water you could drink to flush a toilet? This is a huge waste of a precious resource, especially in the epic drought we’re experiencing in California. This project is a way to save water in style, using a plastic coated Plyboo sink and a sleek faucet by Moen.


A single toilet flush uses about 3 gallons (13.5 Liters) of potable water. A toilet tank sink works by routing the water that would normal go into the tank, which is clean water from the supply, through the sink on top of the tank. From the there, the resulting graywater goes into the tank and then into the ball for flushing.


The only peculiarity of this type of sink is that you have to turn the faucet on while flushing to refill the tank. That, and of course, washing your hands on the toilet. But hey, get over that. This is a foolish waste of water. Why not make it do double duty?


To create his sink, Jon-A-Tron used Plyboo (plywood made from bamboo) for the wooden tank, Ultra-Glo polymer coating for waterproofing, and a very fancy, expensive Moen faucet. This Instructable was sponsored by the well-known bathroom fixture company, hence the $600 faucet. If you’re going to build this, you could obviously use a much cheaper fixture.


Here’s a video of Jon-A-Tron briefly describing the build and showing how the faucet operates:

YouTube player


You can see the full project and find templates for this build on the project’s Instructable page.

This project is from a series on Instructables sponsored by the plumbing equipment company Moen. You can view all of the projects in the series on the Moen landing page on Instructables.

19 thoughts on “Build This Water-Saving Toilet Tank Sink

  1. Brad says:

    I know this is “Make” not “Buy”, but you can buy retrofit toilet tank sinks at most home improvement stores.

    1. Gareth Branwyn says:

      Some people like making things for the sheer joy of doing so, not just because they can’t buy the thing they are trying to make.

      1. sophiacamille says:

        also, this one is wayyyy prettier than standard porcelain ones I’ve used. Nice write up, Gar

        1. SportTime says:

          If you could see that sink in a few months to a year I guarantee it would not look “pretty.”

  2. Leif Burrow says:

    Beautiful build but I don’t think the toilet tank sink is a great idea unless you live in the middle of the desert and water is really really precious.

    The thing is that all that soap, dirt and bacteria isn’t going directly down the drain. It will sit and fester inside the tank until it gets flushed. Then when it does get flushed, even if you held down the handle until no more water was flowing there is going to be maybe a cm or so of water that just sits in the bottom. That means that while you may eliminate the majority of the scum upon flushing there is always going to be a sample of very type of bacteria that ever got washed in ready to repopulate the new water.

    If you went away or something (or just used your other bathroom) and so didn’t flush for a while it could get pretty rancid. Also.. keep in mind, all those toilet parts, inside the tank, they do not last forever. They are meant to be replaced.. usually by the owner. Some day you will have to stick your hands down in that thing!

    1. SportTime says:

      agreed. And good luck keeping that bamboo sink clean over time. There’s a reason EVERY normal sink has rounded corners and no seams.

      1. Judith Young says:

        .❝my neighbor’s mom is making $98 HOURLY on the internet❞….A few days ago new McLaren F1 subsequent after earning 18,512$,,,this was my previous month’s paycheck ,and-a little over, $17k Last month ..3-5 h/r of work a day ..with extra open doors & weekly paychecks.. it’s realy the easiest work I have ever Do.. I Joined This 7 months ago and now making over $87, p/h..Learn More right Here….
        ➤➤➤ http://GlobalSuperEmploymentVacanciesReportTiptop/GetPaid/$97hourly… ❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦.❦

    2. Charles says:

      Also, I’d be worried that hand soap might play hell with all the rubber parts in the tank. Even chlorine in the water eats them up over time.

    3. Icicle says:

      You make some good points, but if the sink is situated properly, the sink drains into the overflow tube and into the bowl of the toilet, not the tank.
      In a toilet valve, there are 2 exits for the water. The first is at the bottom near where the valve penetrates the toilet tank, and the second is near the top of the valve, which is normally routed into the overflow via a hose.
      When you flush, the bottom outlet fills the tank, and the top refills the bowl of the toilet and ensures that the trap is filled with water.
      In this design, it appears that the sink is only being used to refill the bowl and trap of the toilet, not the tank of the toilet.

  3. Al Jalaikakik says:

    There’s nothing “Foolish” about proper sanitation. Certainly it’s laudable to come up with clever methods of using waste water, but I live in a high rise where I’m lucky if TWO flushes will actually clear all the waste from my toilet. This setup looks to be a MASSIVE waste of time.

  4. Linenoise says:

    Since ’94 water closets only use 1.6 gallons per flush. If you’re still using 3 gallons per flush the best way to save some valuable water resources is to buy a new fixture to replace your 20+ year old toilet.

    1. austin943 says:

      I have to flush those newer toilets 2 or 3 times after I take a dump. With the old style, only one flush was needed.

      1. Joe says:

        Something is wrong with your colon.

        And you can always spray some coating on the inside when it’s dry.

        1. austin943 says:

          I eat a lot of roughage. A cow could not put out more than I do.

        2. Lisa_LampoFat says:


  5. fstedie says:

    This is one of those “projects” where money is not the issue but rather a display of fanatical eco-centric posing. There is no real water savings here and it is neither a practical nor hygienic way to wash your hands. It was originally posted in Instructables and being a “sponsored” article, they remove any and all comments that don’t support this ridiculous idea.

    1. jhonsonm says:

      why you don’t attach with makezine If you wana get a reasonable income through laptop and if you have a reliable internet connection then you should be able to know how you make your income by laptop.this is very simple to know just vist my website

      and sign up there for more details One Time Learn

  6. John Daniels says:

    This is pretty standard practice in Japan for most toilets. They almost all have little sinks on top. You don’t use soap with the sinks. The toilet doesn’t run long enough after a flush to allow you to completely lather up and rinse off all the soap. The point is that you can give a little rinse after urinating. You still have normal sinks with soap for washing up after a big job. It’s an extra little step to help keep the inside of your bathroom a little more sanitary. Instead of grabbing the faucet handles with possibly pee splattered hands (you know good and well you don’t wash the faucet handles while washing your hands) and then grabbing them again after having JUST cleaned them, you can grab them with mostly clean hands and everyone is a winner. If you haven’t used one of these toilet top sinks, don’t be so quick to poo-poo on the idea. It’s definitely better than the current system you employ.

  7. Jan Terje Hellemsbakken says:

    This idea would not be half bad if connected to a urinal. Add a hands free water fixing.

Comments are closed.

Discuss this article with the rest of the community on our Discord server!

Gareth Branwyn is a freelance writer and the former Editorial Director of Maker Media. He is the author or editor of over a dozen books on technology, DIY, and geek culture. He is currently a contributor to Boing Boing, Wink Books, and Wink Fun. And he has a new best-of writing collection and “lazy man’s memoir,” called Borg Like Me.

View more articles by Gareth Branwyn
Maker Faire Bay Area 2023 30% off early bird ticket sales ends August 31st, 2023!

Escape to an island of imagination + innovation as Maker Faire Bay Area returns for its 15th iteration!

Prices Increase in....