As part of my ongoing downsizing, my new house's bathroom will be smaller, so I'm looking at installing a toilet/sink combo to

  • save space,
  • reduce construction costs by making the bathroom as small as possible, and
  • reduce my water usage

Toilet-sink combo

What did you find you had to change in your behavior when switching to this setup?

Edit: The bathroom's finished size will be approximately 3' (0.91m) x 6' (1.83m), thus necessitating the combo device or some other equally-compact setup.

  • integrated toilet and basin, is it just a cold feed or is it hot and cold ?
    – user2626
    Sep 30 '15 at 18:50
  • @kenny It is supplied from the faucet you have connected to the toilet, so you would need to plumb in the hot water (or a mix) if that's what you want.
    – BryanH
    Oct 6 '15 at 16:32

They are ubiquitous in Japan (image), which may be a lead for tracking one down.

As the picture shows, they also come with the sink/tank part removed (usually triangular, to fit in a corner), so you can place it wherever you like.

I think it may (and does in Japan) replace a normal sink in a guest toilet, but for all other purposes, you need at least another sink.

Here's why

  • Your waste water will sit inside the tank, and that waste water better be just clear water, otherwise you will have to clean the tank from the inside every week or so.

  • You would also have to install an extra faucet, unless you want to flush the toilet everytime you wash your hands.

  • As @berry120 mentioned, the sink will be rather small (which is the point) and unusable.

I actually regard them ideal for guest toilets just for the reason you mention, but they are not a replacement for a regular sink.

  • 1
    +1 for the clean-the-toilet-bowl requirement and reference. From what I've read, the sink stops working when the float rises above a certain level, necessitating a flush.
    – BryanH
    Jan 30 '13 at 19:34
  • Why don't the tanks just have an overflow hole that goes straight to the toilet? Seems dead obvious and simple to implement. Normal tanks also have an overflow afaik. Nov 18 '19 at 15:08

I haven't installed or used one myself, but my initial reaction comes as the following:

  • Saving space - yes, it definitely would. However, it looks like it does so at the cost of accessibility, it looks rather awkward leaning over the toilet bowl to get to the sink each time, and I could well imagine that getting annoying over time.

  • Reducing construction costs - are you sure? Sure, there's less there but the novelty of this particular item leads me to believe that unless you know a source you can get it from cheaply, you may not be saving as much as you think.

  • Reducing water usage - yes, it will definitely do that over a separate sink and toilet, but not over a sink with a waste pipe feeding into the toilet.

So while the above could work in some form, I'd actually suggest another idea - could you not get a conventional sink and run the waste outlet to the toilet bowl? You don't have the same space savings, but small sinks don't take up too much room anyway, and this way you still have the same water conservation in effect.

  • 1
    I do not see how an integrated design would in itself save any water at all. As you mention, it is always possible to feed the toilet reservoir with waste water from the sink, if the water savings are your goal.
    – Prymaldark
    Jan 30 '13 at 2:35
  • Thanks for the thoughtful response! I updated the question vis-a-vis the construction costs: the room can (will) be really small; adding a separate sink would require enlarging the room accordingly. The "annoying factor" is definitely a concern, at least until I get used to it.
    – BryanH
    Jan 30 '13 at 19:28
  • 3
    Thanks to Elizabeth for this: "there is a product called "SinkPositive" that allows you to convert a conventional toilet into a toilet-sink combo. The product replaces your existing tank lid and takes about 5 minutes to install."
    – 410 gone
    Aug 2 '13 at 8:04

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