Every bathroom faucet in my house is leaking in roughly the same fashion. They were installed roughly 2.5 years ago (new construction). They are connected via Pex lines. The leak is inside the threaded, brass pipe that comes down from under the handle.

Delta bathroom faucet style

Here you can sorta see the underside with the dark-gray pex connection. Underside of the faucet

And here's the cartridge. Picture of the removed cartridge and it's housing

The odd thing to me is it's every single bathroom faucet (6) on both the hot and cold side. I can't see any way to tell if it's the pex connection and I don't see anything wrong with the cartridge. It is a slow drip-leak out of the inside of the brass coming down.

What I also don't see is any sort of O-ring or washer.

These cartridges are like 25/each so having to suddenly replace all 12 on relatively new faucets is kinda suspicious.

I believe this is the parts diagram for it: https://media.deltafaucet.com/PartsDiagram/DPD-L-2538-DST.pdf

  • 1
    Contact the builder. All six can only be from defective parts or defective labour.
    – crip659
    Apr 10, 2022 at 19:25
  • Are you sure the dark grey is pex? I've never seen dark grey pex. Typically this connection is a braided hose that screws into a shutoff. Could the dark grey be the decorative pvc hose cover described in the parts diagram? Apr 12, 2022 at 7:29
  • Pretty sure it's not any sort of cover. The compression fitting into the valve at the wall is directly on the dark-gray. Nothing slides or move if I take everything apart like I would think a cover would. I didn't see any markings to indicate what material it was so I assumed pex since it feels roughly the same as everything else in the house.
    – McAden
    Apr 12, 2022 at 13:40

1 Answer 1


Dollars to donuts this is surface water from your sink top and splash water coming down the exterior of the brass. Turn off the water, disconnect the lines, dry everything and flood the sink surface. Check if any water leaks down.

  • Seems like a good possibility. Note: After sink #1 is thoroughly dried, go get a cup of water from sink #2 and pour it on the counter top around sink #1 so you know 100% whether the water is coming from an internal leak in #1 or from the surface. If you pour the water from sink #2 and you end up with water below, you know it's leaking from the counter top under the base. If it's still dry underneath, then it's actually internal to sink #1.
    – FreeMan
    Apr 11, 2022 at 13:05
  • I'll give this a shot. If this is what's going on, what's the recommended solution? silicone seems like it'd be a bad option visibly. The gasket on these things is really thin and crappy and doesn't line up well with the pre-drilled holes in the granite.
    – McAden
    Apr 11, 2022 at 13:55
  • Generally bathroom silicon is the go to option. Stainless faucet with stone sink generally means transparent. There are good youtube videos that will show you good techniques that allow it to look nice. Apr 11, 2022 at 16:25
  • Haven't yet a chance yet today because I've been working but in regards to this answer I did want to point out that the drips are definitely coming from inside the brass
    – McAden
    Apr 11, 2022 at 19:04
  • These are delta faucets. I have a hard time believing that 6 could fail in 2.5 years. The brass is just a mount point to anchor the faucet to the sink it isn't meant to be sealed to the faucet in anyway though if the leak was the deck you would expect it to be traveling the outside of the brass. How much water is coming down are we talking a drop a second or is this not enough to fill a measuring cup in a day. Is the water only coming out when the faucet is used or all the time? Apr 12, 2022 at 7:32

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