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I have 2 faucets at my kitchen sink: one for regular water stuff and the 2nd for drinking water. Lines running from the drinking water faucet are 3/8" female compression. My ecopure inline water filter has 1/4" male compression (un-removable), at both ends. I refuse to use any other inline water filter as I have tried several and only this 5 year ecopure removes all the odors/tastes. ecopure changed the connections a few years ago.

I've figured out how to run from the kitchen sink cold water supply/shut-off valve (3/8" x 3/8" x 1/4" tee & 1/4" line), but cannot find a 1/4" female compression to 3/8" male compression adapter. I can attach a 1/4" female compression line but will then need a 1/4" male compression to 3/8" male compression. Any help is appreciated as I have been searching for a month now.

  • 1
    When faced with this problem, I generally bring all the parts to the large big-box hardware store (or the local one) and hack away until I find a combination that works. I think that a diagram would be very helpful. You can turn a 1/4 inch line into a 3/8th inch line by running a 1/4-1/2 and a 1/2-3/8ths adapter.
    – gbronner
    Oct 23, 2015 at 1:25
  • Did that and the adapter does not exist. Tried Lowes, Home Depot and various other hardware stores - also online. I do not want to use plastic tubing. Oct 24, 2015 at 1:00
  • You don't need to use just one adapter. You can use a 1/4-1/2 and a 1/2-3/8ths on both sides... anything that gets you from one end to the other.
    – gbronner
    Oct 26, 2015 at 13:51

3 Answers 3


Since it seems that you already have the lines, I think all you need is a compression adapter fitting like this:


It will screw onto the female 3/8" compression on the drinking water faucet and allow you to connect a 1/4" compression line to it (from the filter).

This is one of the most commonly sold compression adapter at Home Depot, so anyone in plumbing should be able to point you to it (if you're in the US... I'm sure Lowes and others sell it to. Quite common.

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  • Comment from an amazon buyer: I wanted to use one of these for converting an easy to find sink shutoff to an icemaker outlet. The picture would seem to indicate it could do that - but no it won't. The one I received has male compression threads on the 1/4" side, not female - i.e. it is meant to attach to a piece of 1/4" tubing. And it's female on the 3/8" side. Oct 24, 2015 at 1:00
  • I will not use plastic tubing. That's my problem, I guess. I have decided to return the drinking water faucet and purchase one that accepts a 1/4" compression line. I am glad your solution worked for you and thank you for taking so much time to help. Oct 24, 2015 at 1:01

heres the link for the fitting you will need http://www.amazon.com/gp/product/B00ITPFJ72?keywords=3%2F8%20x%201%2F4%20compression%20fitting&qid=1445559798&ref_=sr_1_5&sr=8-5


I had a similar situation, and I ended up making my own adapter from a few parts. I had a 3/8" push connector on my filter, and a piece of 3/8" tube. I had to attach that 3/8" tube, to a 1/4" male compression end on the faucet.



  1. Cut a short piece of 1/4" tubing (~1").
  2. Push one end of the 1/4" tube into the coupling.
  3. Put compression nut and ferrule on, and sleeve in other end of 1/4" tube.
  4. Push one end of the 3/8" tube into the coupling.
  5. Connect 1/4" compression nut to faucet.
  6. Push other end of 3/8" tube into push connector on filter.

Finished Adapter

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This exact adapter might not work for you, but you should be able to bodge something together with parts from the local hardware or home improvement store.

  • Not going to use plastic tubing in my drinking water supply. I am returning the faucet and purchasing one that accepts a 1/4" comp. line. Thank you for your time! Oct 24, 2015 at 1:02
  • What type of pipe are you using?
    – Tester101
    Oct 24, 2015 at 3:39

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