I am trying to locate a leak that has reappeared.

The leak appears on my kitchen countertops, it actually is leaking on top of one of my corner cabinets. Theres a bit of a gap between the cabinet and the soffet and I can see it.

Immediately above the cabinet there is:

  • master bathroom - Original to 1970s house.
  • guest bath - redone this century
  • associated drain/vent stacks

The original 'fix' for this leak was a year ago under my home warranty. Plumber determined that the tub, drain, etc. were sealed but there was a leak/gap in the linoleum floor in the master bath. The leak was not leak, rather just people being wet or splashing in the bathroom. This was not covered by the warranty (different topic), so I got a tube of silicone caulk and sealed the gap and the entire edge of the linoleum floor.

This leak reappeared today. I pulled the tub drain and overflow cover and resealed with plubmers putty. Its raining, so I went in the attic and checked that the vent stack was dry. I also filled and drained the guest bath tub.

My primary suspect is this unsealed floor again. What else should I investigate?

I could care less about the master bath, I do care about the nearly new cabinets in my kitchen and inside-the-wall water damage.

  • If you can rent/borrow an thermal camera, you should be able to see the leak through the wall (as long as the water temperature is either higher or lower than the walls ambient temperature). If you have the cash to buy one they are great for loads of stuff, like optimizing your insulation as one example.
    – Tester101
    Jun 15, 2011 at 19:05

2 Answers 2


Options include looking for discoloration on surrounding areas and even putting a paper towel or Kleenex in suspect areas in order to detect a small leak that may not have been sufficient to create noticeable discoloration. Depending on the volume, you may be able to hear dripping in order to help trace the leak. And you may wish to reconsider whether the initial diagnosis was correct or whether the repair was sufficient.

Here are three causes that weren't obvious to us that you may wish to consider:

(1) Around the tub spigot: We had a situation in which we had a leak from a bathroom on the ceiling of the dining room beneath it. We re-caulked the tub and shower surround, did a small test, didn't see any water leaking, and thought we'd taken care of the problem. The next time someone showered the leak reappeared. We eventually figured out that the problem was around the spigot: Water from the shower was hitting the spigot, and because there was not a good seal around the spigot, water was running behind the spigot, down to the floor, and eventually into the dining room below.

(2) The actual copper supply line connections--if you're fortunate enough to have access to them without tearing out the wall: In another house, one with only one floor, we thought we had a leak in our shower pan, but during a remodeling discovered that the hot supply line had not been soldered correctly and water had been squirting out between the wall and eventually out through the brick in the adjoining exterior wall.

(3) Diversion due to insulation: We had another leak that we thought was due to a problem with the flashing between the roof and adjoining siding. After tearing up the roof and the ceiling of the room being damaged, we discovered that the problem a poorly-sealed nail in the roof itself. However, this location was several feet away from where water damage showed up. In this case, the insulation directly below the small leak was sufficient to keep the water from running straight down. Instead it wound around and into another room.

  • #1 is a strong possibility. What is the right way to seal that? Caulk? Putty?
    – Freiheit
    Jun 15, 2011 at 15:53
  • 1
    Around the outside, where the outside of the spigot touches the wall or side of the tub, use the same high quality caulk you've used for sealing other similar places where the tub or shower meets the wall. (Depending on your arrangement, you may also find a way to use plumber's putty on the inside.) Good luck. Few things are more frustrating than a persistent leak.
    – Lee Wright
    Jun 15, 2011 at 21:05
  • Accepted. My tub spigot was both poorly sealed and corroded. After removing it I sealed the gap between the tile and the pipe with plumbers putty. 2 showers later, no leak! I have to replace the spigot, but thats no big deal.
    – Freiheit
    Jun 16, 2011 at 14:11

The best way to find this may be to put a hole in your kitchen ceiling. Cut out an opening in the drywall and have a look. You can check for water damage that may point you to the source, or get someone to take a shower and try to find it in the process of leaking.

Another thought: if the issue is happening during the summer, check your AC drain lines if you have an AC unit in the attic. If they clog, condensation will backup and start draining into your home.

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