2

I bought a countertop dishwasher. Home Depot did not have adapters to connect my faucet to the included quick-connect adapter. I have also heard that the hoses in pull-out faucets are not meant to withstand full line pressure as done by this blog post.

So I want to install a tee on the hot water line and connect that to the dishwasher. Here's what I have to work with:

  • Hot water pipe: 3/8" compression (male)
  • Dishwasher input: thread OD 26.33mm (1.037"), 4 threads per 7.28mm (0.287", 14 TPI). I think this is 3/4" MIP/NPS.
  • A hose that connects to dishwasher and terminates with a nut (14.48mm/0.57" ID) and washer. This matches a male end on the quick-connect adapter which is 15.4mm (.607") OD, 7 threads in 10.16mm (0.4"). I am not sure whether this is M16x1.5mm, 5/8"-18TPI, or something else.

I would like to re-use the hose but don't know what it terminates in. So without that, here's what I've got using hardware store parts:

wall: 3/8" Compression male
3/8" compression tee
3/8" compression supply line
3/8" compression to 3/4" MIP (NPT) adapter
3/4" FIP (NPT) coupling
dishwasher input: 3/4" MIP

wall==>     >══╦══>   >==================<      <==>                   >==<        <====dishwasher
3/8 comp       v        3/8" comp hose     3/8 comp to 3/4 MIP   3/4 FIP coupling      3/4" MIP
          3/8 comp tee
               v
          to sink hose

This is a lot of parts and brass adds up quick. How can I reduce part count? I tried looking for e.g. a 3/8" comp to 3/4" FIP hose, but even McMaster-Carr only has 3/8" comp to 1/2" FIP. Do they make 3/8" comp to 3/4" FIP bushings? This guy with an identical-looking dishwasher spent $90, which I do not want to do.

Improve this question
4
  • 1
    Have you tried at a plumbing store/shop? Stores like where you went, usually only stock stuff that moves fast and is common for most things.
    – crip659
    Mar 29, 2022 at 0:12
  • 1
    Do you want to use the quick-connect? Or, in any case, what's the other end / half /part of the quick-connect got on it for threading? Many similar quick-connects have an option to GHT (Garden-Hose Threads) for clothes washing machines (and some portable dishwashers) which can easily be gotten from a boiler drain valve (that you'd Tee off your supply line.) Indeed, I'd wonder if your dishwasher input is actually GHT, not NPS. That would mean a mis-measurement of pitch, but that can happen.
    – Ecnerwal
    Mar 29, 2022 at 0:46
  • You could add another line coming through the escrusction that the faucet is mounted and add an additional hose bib there, That should be fairly inexpensive,
    – Gil
    Mar 29, 2022 at 0:48
  • @Ecnerwal unfortunately, I only got the plastic end of the quick connect (it was a used dishwasher). I know that GHT is common for inputs on the rolling "portable" dishwashers, but I think the threads are too fine.
    – WindowsEscapist
    Mar 29, 2022 at 4:31

2 Answers 2

Reset to default
2

The faucets for old clawfoot tubs also have a 3/4" MIP connection, and they make braided flex supply lines for 'em. Use the 1/2" FIP x 3/4" FIP flex line instead of the 3/8" flex you were going to use. Adapt from the 3/8" stop valve (or a 3/8" comp. tee, if necessary) directly to 1/2" MIP with a little special adapter made for exactly that scenario, to accept the tub flex, which will attach directly to your portable dishwasher . These are likely plumbing shop items, as opposed to "big box" (and don't be surprised if they are cheaper at the plumbing shop...

enter image description here

enter image description here

Improve this answer
5
  • Total cost prolly less than $35, and fewer fittings
    – Jimmy Fix-it
    Mar 29, 2022 at 2:58
  • Thanks! I'll find a plumbing store and report back.
    – WindowsEscapist
    Mar 29, 2022 at 4:32
  • 1
    An even better option (IMO) would be to change out your supply valve (angle-stop valve) with a dual-outlet valve that has a 3/8" compression outlet (for your faucet) and a 1/2" MIP outlet (for the dishwasher; they make them, I have one under my kitchen sink). This would further reduce the number of adapters/fittings, but would require more work, money, and shutting off the water.
    – Jimmy Fix-it
    Mar 29, 2022 at 16:17
  • Nice, I'd do it if dual-outlet valves were cheaper than the tee and adapter, or if I owned the building. Swapping out a part instead of just adding means I have to store the single valve for when I leave this apartment. Have yet to visit plumbing store, hopefully they have a long enough hose.
    – WindowsEscapist
    Mar 29, 2022 at 17:53
  • No luck on the hose. I'm accepting this answer, since it gives one way to reduce part count, and adding what I actually did for future confused dishwasher buyers. Cost under $35 as you predicted so it all worked out.
    – WindowsEscapist
    Mar 30, 2022 at 2:17
1

The plumbing store didn't have a long enough 1/2" to 3/4" FIP line and I was getting antsy. So I bought something close to my original parts list for a total of $30.70. For future readers, here is what I got:

  • 3/8" compression tee, 1 female 2 male. $10.39, #4225030
  • 6' supply line, 3/8" compression. $10.64, #DW872
  • 3/8" compression to 1/2" MIP connector. $4.34, #102631
  • 1/2" FIP to 3/4" FIP coupling. $5.33, no part number.

I installed the tee right after the hot water shutoff valve and connected the sink hose and dishwasher hose to it:

installed 3/8" compression tee

I connected the 3/4" to 1/2" adapter to the dishwasher, the 1/2" to 3/8" comp adapter to that, and then the hose to that. It is very easy to crossthread a plastic piece when you're attaching a metal piece to it. I used PTFE tape and wrenched it pretty tight, but it still drips a couple drops during the dishwasher cycle, hence the tray underneath.

hose to adapters to dishwasher

And finally, I just pointed the original drain line into the sink. The PVC under the sink doesn't have an easy place to tee in the hose, and this is a $25 dishwasher, so I didn't feel like putting more time into the project.

ziptied hose draining into sink

Improve this answer
2
  • 1
    I'm glad it worked out, if you ever have to do it again, there is a tailpiece for the sink drainpipes commonly called a "branch wye" or "dishwasher wye" that is made to accommodate a hose connection to the under-sink drain system. It would make it a cleaner installation.
    – Jimmy Fix-it
    Mar 30, 2022 at 3:48
  • I know, there's just not an obvious vertical section of pipe between sink drain and P trap to swap for a wye. I'd have to find a very short wye or drop all the drainpipes.
    – WindowsEscapist
    Mar 30, 2022 at 7:16

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.