I recently installed a new faucet into our sink bathroom as well as reinstalled both cold and hot water lines. I realized that there was some water on the bottom of the cabinet. I put a tiny plastic bin and after 8 hours there was only a little bit of water. I checked where it was coming from and it seems to be leaking from above the plastic cap, above the metal nut.

On the hot water line, the white plastic cap/nut covers the entire opening hole for the faucet threads, but it doesn't on the other side where it is leaking. I am pretty sure it's not coming from the metal nut that I tightened correctly.

How do I fix this leak if it is indeed coming from above the plastic cap area and what would cause it? Can I just use some plumbers epoxy (from Ace Hardware) to seal the rest of the opening? I have provided pictures below along with a red circle showing where it's wet ( as soon as I touch this white cap after a while, a couple of drops of water will immediatelly fall down).

This is the leaking side Leaking side

This is the side that is fine enter image description here

This is the small amount of water collected after 8 hours enter image description here

1 Answer 1


Nothing above that should be leaking on a new faucet.

If it is, the faucet is defective, so contact the maker.

The joints you connected the water lines to are below that point, and the white plasic nut just threads on to hold the faucet to the countertop.

Trying to plug it with epoxy will just move the leak to the top of the counter, most likely, and does not address the defect.

  • ...as for countertop hole coverage, you can loosen both and slide the faucet around, to the extent that the holes are bigger than the threaded stems inside the nuts. But that's got nothing to do with a leak.
    – Ecnerwal
    Mar 11, 2023 at 17:31
  • this was a new faucet, could a bad seal cause this? If water from the countertop seeps in between the sealing, could it be causing these leaks? When I installed the sink, it came with one of those clear gaskets. I didn't have any silicone on me at a time and didn't seal it chemically. Would it be worth putting silicone on the seal and seeing if that stopped the leak? It would have to be only on the right side it is not sealing properly.
    – HotWheels
    Mar 11, 2023 at 17:36
  • ok just checked the seal and it is indeed moving on the right side and water is seeping through. I will have to take it apart and put a proper seal this time.
    – HotWheels
    Mar 11, 2023 at 17:39

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