I am attempting to install a bidet attachment I ordered online. The first step is to shut off the supply valve and empty the toilet, as it attaches on between the supply valve and tank.

I am unable to fully shut off the water supply. The supply valve opens fully and it will stifle the supply water somewhat but not completely off it. I am afraid to force it or use a tool with my level of plumbing knowledge. Could any helpful people give me advice on a course of action? I see a screw on top of the valve— I’m deathly afraid of losing some piece of it and flooding the bathroom. As much as I can hand turn it, it just isn’t enough to cut off the supply to do the work needed.

I could shut off the entire house water supply if all else fails but I’d like to be able to turn off the water supply valve locally.

The supply valve

supply valve view other side

  • 1
    Looks like a 1/4 turn valve. There's no forcing those, so don't. Always know where the main shut off is before doing anything.
    – Mazura
    Commented Sep 1, 2018 at 0:19
  • Typical inexpensive consumer valve ; replace it as needed. Commented Dec 14, 2020 at 16:08

1 Answer 1


Getting it to shut off completely is unnecessary. There are plenty of SE questions about swapping a valve or trying to get it to close more if you really want to. You're talking about a down time of minutes, not days or weeks; that's when I would suggest that, or taking it off and capping it.

  • Turn the valve off as much as possible.

  • Flush the toilet.

  • Take the supply line lose from the toilet and let it, and the toilet, drain into a bucket.

  • Have towels down on the floor because it's going to get a little messy as you install the new equipment as fast as possible and hook everything back up.

  • Don't be in such a rush that you cross-thread or over tighten. A little water never hurt anything.

If you're really worried get a tiny brass cap to put on the valve while you work. It's probably 3/8ths compression thread and usually found in the isle with faucet repair parts - alternatively, get a 3/8ths compression thread plug to put into the supply line. Both usually require a few wraps of PTFE tape to actually seal - but again we're talking minutes, so whatever: towels, a bucket, and get 'er done.

  • 1
    Thanks Mazura. I went the whole house off route! Now I’ve got everything installed. However the T adapter is leaking where the hose goes to the bidet. Slightly, enough to be a problem. Now I’m wrapping the PTFE tape around each thread and praying it fixes the leak. Cuz I have to run back out to the curb each time! Ha. If these things fail I shall be heeding your advice when the hardware store is open and I can get a few plugs. The other threads I saw on supply valves were actually what terrified me—one said you could lose a ball in the valve if overtightening a screw and then it’s leak city.
    – thetallone
    Commented Sep 1, 2018 at 1:35
  • @thetallone - a very slight drip might plug itself with minerals. That's not ideal, but if you've put it together six times and all you get is a drop every 30 seconds, put a pan under it and try to wait it out.
    – Mazura
    Commented Sep 1, 2018 at 15:11
  • 2
    Please, please please replace the stop valve while you have the water shut off to the house. Those valves provide a local point to stop the water for maintenance and for leaks. If something leaks in the future and you are not there, the person who tries to turn if off likely will not know how to quickly shut off the main... and your house is flooded. Commented Sep 1, 2018 at 15:56
  • @JimmyFix-it - then they'd be breaking the rule: know where the shut off is. But yeah, if you've got it shut off and you have to go clean all of your aerators anyway, now's the time to swap the valve.
    – Mazura
    Commented Sep 1, 2018 at 16:04

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