# What Compression Fitting Do I Need? **URL:** \ **Category:** Factual Questions\ **Created:** [October 5, 2019, 2:06am UTC](https://boards.straightdope.com/t/what-compression-fitting-do-i-need/841296 "2019-10-05T02:06:00Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\ **Post date:** [October 5, 2019, 2:06am UTC](https://boards.straightdope.com/t/what-compression-fitting-do-i-need/841296/1 "2019-10-05T02:06:00Z")
I just bought a new fridge, but the delivery team won’t connect the water supply line to the existing water supply line. My problem is I have a 3/8" male threaded connection at BOTH the end of the copper supply and a 3/8" connection at the fridge intake. So, what do I need to make the connection? Googling around, I keep seeing a 1/4" compression fitting with two female ends to make the connection. So, is a 1/4" female threaded connector the correct mate for 3/8" male threaded connector? It seems logical, but is that correct? ---
**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\ **Post date:** [October 5, 2019, 2:07am UTC](https://boards.straightdope.com/t/what-compression-fitting-do-i-need/841296/2 "2019-10-05T02:07:49Z")
Also, are brass fittings still acceptable for potable water service? Googling around, I saw something claiming it was until 2014. If so, can I find the desired fitting in copper? ---
**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\ **Post date:** [October 5, 2019, 2:11am UTC](https://boards.straightdope.com/t/what-compression-fitting-do-i-need/841296/3 "2019-10-05T02:11:31Z")
Are you sure it’s a compression fitting ? From your description it may we’ll be that one is a compression and the other is NPT. Post some pics so we can be certain. ---
**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\ **Post date:** [October 5, 2019, 2:17am UTC](https://boards.straightdope.com/t/what-compression-fitting-do-i-need/841296/4 "2019-10-05T02:17:30Z")
If you are sure that you have male compression fittings on both sides - Then a tune like this one will do the job : > **[Everbilt 3/8 in. COMP x 3/8 in. COMP x 60 in. Universal Stainless Steel...](https://www.homedepot.com/p/Everbilt-3-8-in-COMP-x-3-8-in-COMP-x-60-in-Universal-Stainless-Steel-Dishwasher-Connector-7223-60-38-6E-EB/205854141?MERCH=REC-_-pip_sem_mobile-_-205214579-_-205854141-_-N)** > > Everbilt universal dishwasher installation kit includes everything needed to connect your dishwasher. The connectors are corrosion resistant inside and out. Used to connect the water supply to your dishwasher, ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [October 5, 2019, 3:09am UTC](https://boards.straightdope.com/t/what-compression-fitting-do-i-need/841296/5 "2019-10-05T03:09:45Z")
> [@Jinx](#): > > So, is a 1/4" female threaded connector the correct mate for 3/8" male threaded connector? No. Unsurprisingly, it takes a 3/8" female fitting to mate with a 3/8" male fitting. ---
**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\ **Post date:** [October 5, 2019, 3:25am UTC](https://boards.straightdope.com/t/what-compression-fitting-do-i-need/841296/6 "2019-10-05T03:25:03Z")
> [@am77494](#): > > Are you sure it’s a compression fitting ? From your description it may we’ll be that one is a compression and the other is NPT. > > Post some pics so we can be certain. What’s “NPT”? Can you post a picture of an NPT fitting, or such? In the meantime, (tomorrow), I have to figure out how to post a picture. I used to know, but I’ve forgotten and maybe it’s changed. ---
**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\ **Post date:** [October 5, 2019, 3:39am UTC](https://boards.straightdope.com/t/what-compression-fitting-do-i-need/841296/7 "2019-10-05T03:39:46Z")
> [@Jinx](#): > > What’s “NPT”? Can you post a picture of an NPT fitting, or such? In the meantime, (tomorrow), I have to figure out how to post a picture. I used to know, but I’ve forgotten and maybe it’s changed. NPT is national pipe thread. Just go a google search on NPT fittings and you will get many pictures. How did you decide it was compression fittings if you don’t know the difference between compression and NPT ? ---
**Author:** ![Snnipe\_70E](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@Snnipe\_70E](https://boards.straightdope.com/u/Snnipe_70E)\ **Post date:** [October 5, 2019, 4:20pm UTC](https://boards.straightdope.com/t/what-compression-fitting-do-i-need/841296/8 "2019-10-05T16:20:46Z")
> [@Jinx](#): > > I just bought a new fridge, but the delivery team won’t connect the water supply line to the existing water supply line.\*\* My problem is I have a 3/8" male threaded connection at BOTH the end of the copper supply and a 3/8" connection at the fridge intake. So, what do I need to make the connection? Googling around, I keep seeing a 1/4" \*\*compression fitting with two female ends to make the connection. So, is a 1/4" female threaded connector the correct mate for 3/8" male threaded connector? It seems logical, but is that correct? If supply line and fridge both have male compression fittings the solution is easy. Make a female-female connector. Get 1 inch of 3/4 copper tubing. two 3/8 compression nuts and compression ferrols from your local hardware store. Assemble. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [October 5, 2019, 5:02pm UTC](https://boards.straightdope.com/t/what-compression-fitting-do-i-need/841296/9 "2019-10-05T17:02:28Z")
I suggest checking the return policies of the local hardware stores, since this is the kind of situation where one could buy five or six fittings that _might_ work, just to narrow it down to the one that _does_ and return the rest. ---
**Author:** ![PastTense](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pasttense/32/14550_2.png) [@PastTense](https://boards.straightdope.com/u/PastTense)\ **Post date:** [October 5, 2019, 5:44pm UTC](https://boards.straightdope.com/t/what-compression-fitting-do-i-need/841296/10 "2019-10-05T17:44:25Z")
> [@Bryan\_Ekers](#): > > I suggest checking the return policies of the local hardware stores, since this is the kind of situation where one could buy five or six fittings that _might_ work, just to **narrow it down to the one** that _does_ and return the rest. Actually it may easily turn out to be a combination of fittings–particularly if you use a local hardware store–which doesn’t have all kinds of specialized fittings.