I noticed that my toilet was having issues, so I was going to work on it. I turned the value off and discovered the valve doesn't work anymore (This seems to happen alot with 1980s turn valves). So I started looking to replace it, which I thought would be fairly straight forward. But I seem to be having issues finding a replacement that I think will work. I attached a photo of the pipe, because the issue seems to be that I have a 5/8" supply line. I was looking for a push-to-connect (I know those are frowned upon) but I didn't see anything that size. I can solder, even though it's not preferred. Can someone suggest a replacement valve that would make sense?

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  • 1
    Pipe sizes are internal diameter not outside size. 5/8 outside will be close to the standard 1/2 inch pipe size, depending on what the pipe is made from. Quite sure google will find tables with pipe wall thickness, outside pipe sizes.
    – crip659
    Commented Sep 29, 2023 at 16:40
  • @crip659 Thanks!
    – jgauthier
    Commented Sep 29, 2023 at 16:51
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    Personally, I'd be looking at just replacing the guts, as that appears to be a standard supply valve (can't tell for sure since you've limited our view). They make repair kits.
    – Huesmann
    Commented Sep 29, 2023 at 17:29
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    Compression fittings are much better than push-to-connect and require no soldering.
    – popham
    Commented Sep 29, 2023 at 18:39

1 Answer 1


1/2" nominal copper pipe/tubing is 5/8" actual outside diameter.

The hole inside is slightly bigger than 0.500" for all wall thicknesses.

One handy reference, no endorsement, plenty more to be found:


Since there's no sign of threading there, it's probably a soldered valve on copper tubing/pipe.

Get a 1/4 turn shutoff valve to replace the failed valve. They do much better in that type of service than the multi-turn screw valves do.

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    Quite right. I would add that a replacement valve that uses a compression fitting for your very-common 1/2" (nominal) copper pipe is probably the easiest solution. As for me I prefer to solder a 1/2" C x MIP adapter to the pipe so I can use thread-on valves. Either option will require you to cut off that old valve, naturally. Commented Sep 29, 2023 at 19:19
  • If you'll be soldering on a new adapter, or a new 1/4 turn solder type valve, you can remove the old valve by heating it up and pulling it off (un-soldering it) and not lose any pipe length.
    – Ecnerwal
    Commented Sep 29, 2023 at 22:45

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