Detecting waterline leak under sink

[Montalvo]

I'm a homeowner asking for help with a water leak that's already cost me $1,000 fixing a cabinet floor. The cold water line under my kitchen sink is leaking, slowly and intermittently. It happened spontaneously after 16 years with no problems. The leak is coming from somewhere between the shut-off valve and the mesh-sheathed faucet hose, a distance of only three inches. But I can't tell exactly where it's coming from. A 3/8" metal tube comes out of the valve and then enters an adapter connected to the faucet's hose. I've tried tightening all three of the nuts (valve, adapter, hose end) but they appear tight. And when it's leaking, it's not possible to see exactly where the water is coming from. I wondered if it was possible to wrap the pipe with something that would pinpoint the exact point rather than replace all of the suspect sources, including the difficult-to-reach faucet hose.

Ideas?

 

[Reach4]

And when it's leaking, it's not possible to see exactly where the water is coming from. I wondered if it was possible to wrap the pipe with something that would pinpoint the exact point rather than replace all of the suspect sources, including the difficult-to-reach faucet hose.

Yes. Tie strips of cotton cloth etc, and see which is the highest wet one.

 

[Sponsor]

 

[Montalvo]

Yes. Tie strips of cotton cloth etc, and see which is the highest wet one.

Sounds good. I'll give it a try. Thanks!

 

[hj]

the faucet hose is the least likely place for the leak to happen.

 

[Montalvo]

Yes. Tie strips of cotton cloth etc, and see which is the highest wet one.

I used strips of Kleenex and found the leak is above the nut at the bottom of the faucet's hose (i.e., the highest point). That nut is tightened against the adapter as tight as it can go and it still leaks. Is there a washer between the faucet hose nut and the adapter or does it sound like the faucet hose will have to be replaced?

 

[Terry]

How about some pictures, 800 pixels or less.

 

[Montalvo]

How about some pictures, 800 pixels or less.

This photo was 2.6 Mb so we'll see if it's too big.

 

[Dj2]

Do yourself a favor and replace the following:
- Angle stop ($5).
- Supply flex to the faucet ($5).

 

[Montalvo]

How about some pictures, 800 pixels or less.

Here's another photo that more precisely pinpoints the source of the leak.

 

[Reach4]

I think you want a new flex line. I don't know why you have an adapter there. Most flex lines are made to connect to the 3/8 compression thread on the valve.

New valve would be an upgrade.

The flex lines have gaskets, so no tape. You can use a little compound or silicone grease if you like.

 

[Montalvo]

Do yourself a favor and replace the following:
- Angle stop ($5).
- Supply flex to the faucet ($5).

I'm no stranger to simple plumbing stuff but getting to the base of the faucet to either remove it or remove the supply flex isn't gonna be simple. I have a 10" deep sink and my angle wrench for undercounter work is only about 9 1/2". Sounds like it's time to call a plumber.

Thanks so much to all who took the time to respond to my question! You guys are great!

 

[Kreemoweet]

(1) 3/8"-drive crowfoot wrench to fit upper supply line nut, (2) 3/8" socket extension drive(s) as long as necessary to reach the nut,
(3) 3/8" universal joint if the angles prove to be difficult, and (4) 3/8" ratchet wrench at the bottom. I'd like to see
a supply line nut that can defeat that combo!