(warning, language may be imprecise/wrong)

I'm connecting a dishwasher for the first time. Under the sink I have what I believe is a 1/2" OD male threaded supply line. I guessed this based on the fact that the flexible hose has a label that reads "1/2 OD in to 1/2 FIP out". Please see attached picture.

I thought I would be able to buy a 1/2" inlet to two 3/8" outlets, but my local stores did not carry anything like that. I bought this dual outlet valve, but the fitting was too large for my supply line.

I spoke with two different people at HD, and both of them seemed really confused that my supply line was 1/2" OD. They kept trying to get me to buy the 1/2 FIP again even though I had already tried it.

I tried to buy a 1/2" OD to 1/2" FIP adapter, but couldn't find any at HD.

Thank you.

enter image description here

enter image description here

  • Please carefully measure the outside diameter of the water supply pipe/tubing that you want to add a tee + valves or multi-outlet valve to, and add it as a comment. The picture alone is not helping us determine what you really have here (I would have bet $ that the threaded fitting soldered onto the pipe in the picture was 1/2" iron pipe thread, but if the valve you linked to was "too big", then it is something else). Commented Jan 2, 2017 at 1:50
  • For the life of my I can't find my digital calipers even though I was using them today. I'll add the measurements once I find my tool.
    – mrtsherman
    Commented Jan 2, 2017 at 2:05
  • Jimmy Fix-it - found the calipers. My mom was over. She put it in the dishrag drawer. The copper pipe itself is 0.5 inches measured on the outside. The threaded portion measured 0.66 inches on the outside. I did not measure the inside of the threaded portion. Can you help me identify what I'm working with here?
    – mrtsherman
    Commented Jan 2, 2017 at 2:13

2 Answers 2


OK, so your supply line is not typical (typical would be 5/8" OD copper pipe). Your line is 1/2" OD tubing (sometimes referred to as refrigeration or ACR tubing).

Also not typical (and IMO totally wrong) is the fact that someone has soldered a fitting with 3/8" MIP (male iron pipe size) onto the tubing and forced a flexible supply line with 1/2" compression threads onto it. That would be the flex supply end that was labeled "1/2" OD".

You need to cut off the threaded fitting that is soldered to your line, then install a compression adapter. If you want to use the multi-outlet valve you already have, use a 1/2" compression X 1/2" MIP (male iron pipe size) adapter like this: enter image description here

Of course, this will necessitate using a new flex supply line to fit the outlet size of your valve (3/8" compression).

  • Found this at Lowe's. It would seem to satisfy all my needs (independent shut offs, convert 1/2" copper pipe to two 3/8 lines. Would you agree? lowes.com/pd/Apollo-125-PSI-Copper-Dishwasher-Connector/…
    – mrtsherman
    Commented Jan 2, 2017 at 14:58
  • It is my suspicion that the inlet (labeled 1/2" compression) is actually designed for 1/2" (nominal) copper pipe, i.e. 5/8" OD, and will not work for you. If you first convert to standard pipe thread with an adapter like shown above, you easily will be able to find a dual 3/8" outlet valve like the one in your link. Commented Jan 2, 2017 at 17:01
  1. If you use that valve and your dishwasher starts leaking one day and your replacement takes a few days to arrive, you'll have no hot water to your sink. You should use a tee with a valve on each end of the tee so you can control the water flow independently. In fact, some cities require this. I learned this the hard way by failing my plumbing inspection by using the valve you linked.

  2. The label you describe is kind of confusing. OD is typically used to describe pipe size, not fitting size. 1/2" FIP is used to describe pipe thread size. If 1/2" is indeed too large, maybe you should try a 3/8" sized fitting? Just to be sure, can you update the question with a picture of the label?

  3. Finding copper/brass FIP/MIP fittings is going to be difficult and/or expensive. It might make more sense to buy a cheap cutter and get some shark bite fittings. Or if you want to be adventurous, solder it yourself..

Here is how I did it

  • Thanks for the advice about the independent shut-offs majikman. I'll likely do that instead. I debated cutting the pipe, but figured I should probably try and learn what I was doing before trying that route. I'd like to do it correctly and know why it is correct. I added a picture of the flexible hose label.
    – mrtsherman
    Commented Jan 2, 2017 at 2:07
  • @mrtsherman i would say that cutting it is the correct way to do it. however, it becomes a matter of whether to solder it or use sharkbite. i'm guessing you probably don't have the equipment to solder, so just buy something like this: homedepot.com/p/…
    – chizou
    Commented Jan 2, 2017 at 2:11
  • Yes, soldering is well beyond what this weekend warrior is capable of tackling. I had never heard of sharkbite before. Thank you for introducing me to it and also thanks for the picture you posted. Now I know what I should be working towards.
    – mrtsherman
    Commented Jan 2, 2017 at 2:19
  • Sharkbite or equivalent is the way to go, be sure you follow the instructions on assembly. They can be removed and reinstalled if need be.
    – Jack
    Commented Jan 2, 2017 at 2:37
  • Sharkbite fittings are for nominal copper pipe sizes: 1/2" Sharkbite fittings fit 5/8" OD copper pipe. For some reason he has 1/2" OD copper tubing and Sharkbite fittings will not work! Read his post including comments, his situation is what happens when well-meaning DIYers browse the Bigbox plumbing aisle to find "a way to make it work". Commented Jan 2, 2017 at 5:43

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