I'm installing a new faucet and it's going fairly smoothly except I cannot seem to get this adapter (unsure that's the right word) to stop leaking.

I've managed to tighten the supply line (top green circle) and bottom nut (bottom green circle) enough where there are no leaks there, but this nut in the middle (red circle) will not stop leaking from underneath (see blue lines; I'm an MS Paint master).

I've taken the supply line off and tried tightening just the nut and it will get gradually tighter until it's loose and I can finger tighten it again

This adapter was installed with the old faucet which I tried to repair, failed miserably, and have since removed.

Do I need to replace this part or is there a way to tighten it I am just not getting?

pipe leak

  • 5
    You have created a "frankenstein" apparatus here. You may want to consider removing ALL of this stuff and installing the correct fittings. The most leak-proof connections are those that don't exist.
    – jwh20
    Jan 1, 2021 at 20:31
  • 1
    That's a lovely bend in your copper pipe. It could be that it's just bent enough that it's curved inside the fitting and no amount of tightening will make it water tight. I second @jwh20's advice, though - buy a new flexible hose long enough to reach to the shut-off valve and just have 2 connections to tighten.
    – FreeMan
    Jan 1, 2021 at 20:56

1 Answer 1


Under that brass nut is a copper or plastic ferrule (sometimes called an olive) if the inside of it is scratched it will not seal.They are cheap so replace it.

Make sure the end of the pipe is smooth and has no spurs that could scratch the new ferrule. If the pipe has shrunk from the pressure of the old ferrule cut that part of pipe off clean up the cut edge and fit a new ferrule.

enter image description here

Plan B: Is if that upper hose is long enough replace the short copper pipe with a connector, seal the connector to the valve and the hose with thread tape.

  • The upper hose is definitely long enough so I'm going to go with option B which is consistent with the @jwh20 provided as well
    – grgdwyr
    Jan 1, 2021 at 20:56
  • 1
    Did not deserve a down vote, over tightening , under tightening or wrong size ferrule all can cause leaks, I had not Heard the term olive.
    – Ed Beal
    Jan 2, 2021 at 8:14

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