I'm trying to figure out how to hook my hot water supply up to my new bosch 500 dishwasher. I have this hose, which does fit the dishwasher:

And attached are images of the hot water shutoff valve under the sink that was hooked up to an old dishwasher and removed by someone else. I have no idea what fitting to get to make these fit, the supply hose I have is too small, can I can't tell what size this outlet is or what combination of parts I need.

I am thinking it might need a compression nut + pipe that then goes into the angle it came with, with another compression nut... but I could be wrong. Please help! It's a somewhat old valve, the house was built in 1989, I would prefer not to have to replace it if I can help it. Or maybe I need a different supply hose?

enter image description here

enter image description here

enter image description here

Edit: I think this is actually the valve that this one is, the other 2 above it are smaller and appear to be the 3/8" variety, but I think the one below it is just an older version of this:


4 Answers 4


I was going to guess the valve outlet is 1/2" compression (if threads are very close together). If not, the it's 1/2" pipe thread. There are no supply lines for 1/2" compression at hardware stores these days. If it is pipe thread, then you're in luck and a different hose can be substituted. Otherwise you'll have to replace the valve. I recommend getting a 1/4 turn valve. They last longer and are more durable, easier and quicker to turn off.

To make your life easiest, I strongly recommend replacing the valve. You will need a 1/4-turn, 1/2-inch pipe inlet and get a 3/8 compression outlet. Most faucets and dishwasher hoses will use 3/8".

Btw, the above brass adapter will not work on your valves if the outlet on the valve is 1/2" compression. You'll have to find a 1/2" female compression yo s 3/8 female compression, which is basically a hose, not an Adapter. You won't find this as an adapter at the hardware store.

  • I am afraid it might be a compression adapter, I've already tried 1/2" FIP adapter, and that did not fit. I guess I'm probably stuck replacing the valve. Do you think the old ferrule will still be usable? I know those are hard to get off and I don't have a lot of pipe to work with under there to cut it off for a new one.
    – shayl
    Feb 8, 2021 at 14:55
  • or does it even HAVE a ferrule, I think that's pvc back there
    – shayl
    Feb 8, 2021 at 20:27

As you can see in the link to the hose for the dishwasher it has a 3/8" fitting.

Your valve appears to be for a 1/2" connection.

You can go to the brass fitting section of the plumbing section and look for a 1/2" to 3/8" adapter.

If yours is not 1/2" then you should be able to find an adapter that will work.

enter image description here

  • Doesn't it look like 3/8"?
    – Seth B
    Feb 7, 2021 at 20:56
  • I don't think it is a 3/8" outlet because the hose I have says its 3/8" but that doesn't go on it correctly. Maybe what I do need is a 1/2" compression. Another wrong thing I had was 1/2" FIP, but I think this is a compression fitting, not iron pipe
    – shayl
    Feb 7, 2021 at 23:12
  • In the US the supply lines are normally 1/2” and 3/4” with that knowledge I would say these are 1/2” fittings also not the common or normal 3/8 that is used for sink supply fittings.
    – Ed Beal
    Feb 8, 2021 at 0:15
  • how can I tell if its an iron pipe connection or a compression connection?
    – shayl
    Feb 8, 2021 at 0:46
  • Actually, I think its compression, the outlet is tapered
    – shayl
    Feb 8, 2021 at 0:57

Here is a chart of nominal vs actual pipe sizes.

From the picture, I would say it is a 3/8" value.

enter image description here

  • The chart is for "iron pipe" sizes. Compression sizes, flare sizes, garden hose sizes, British pipe sizes (not too uncommon on stuff made in China), and so on all have their own "charts".
    – kreemoweet
    Dec 14, 2022 at 4:54

That, my friends is a 7/16 compression fitting. Is pretty uncommon and you can imagine my frustration in discovering it.

  • 1
    Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center.
    – Community Bot
    Feb 18, 2022 at 11:31
  • For what it's worth: adapters from compression thread to pipe thread do exist. (Took me a while to realize that, for some reason, a sculptural garden sprinkler I inherited was tapped with compression thread; once I discovered that I was able to get an adapter from that to hose thread at my local hardware store.)
    – keshlam
    Dec 14, 2022 at 6:03
  • I just ended up replacing this valve, what a stupidly uncommon compression fitting. Who ever thought 7/16 was a good measurement anyway?
    – shayl
    Feb 25 at 3:37

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.