Last year we had a water leak in the drain pipe of our 2nd floor toilet. It dripped onto the 1st floor kitchen ceiling and created a soft, discolored spot over time. That's how we discovered it. We've had the ceiling cut open and the pipes repaired.

Soon, we are remodeling our kitchen. We're installing new cabinets that will have crown molding to the ceiling. (The old cabinets did not go that high.) The place where the ceiling was wet from the leak is directly above where the new cabinets are being installed, so it would be hidden if another leak ever happened. That is, until/unless it got so bad that it leaked through the ceiling and destroyed the new cabinetry.

Since we won't be able to see it, is there anything we can do before everything is patched/installed to detect future leaks?

  • My best option was maybe putting shallow plastic trays between the joists and maybe we could hear it dripping. At the very least, it could temporarily pool in the tray and evaporate... Another idea, though not sure how to do it, is we could redirect water to another part of the ceiling that we can see if it gets wet. It's so little water, though... I don't know if that would work. Feb 15, 2023 at 19:13
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    There are moisture sensors that let you know there is moisture where it should not be, but do not know much about them.
    – crip659
    Feb 15, 2023 at 19:20
  • My biggest concern there is getting power to them. I think there are battery powered ones. I guess we could put the sensor unit on the top shelf of the cabinet and drill holes in the "roof" of the cabinet to run sensor wires to the ceiling above. I guess the concern there is that it might be 10-20 years before it leaks... not sure if the sensors will last that long. Plus the wires in the brand new cabinet are not ideal, but maybe they're a tradeoff that's worthwhile. We can somewhat hide them with white tape/wire tracks. Feb 15, 2023 at 19:27
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    Guttering to a hole over a sink, Or to a drain in the wall to the basement I suppose, but in practice, that sort of thing is hardly ever done. Fix the plumbing right and close it up again is the usual approach.
    – Ecnerwal
    Feb 15, 2023 at 19:35
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    Put an access panel in the top of the cabinet? Stick a leak detector up in the joist cavity where you can reach it through the access panel.
    – Huesmann
    Feb 15, 2023 at 20:10

2 Answers 2


assemble and pipe it properly and there won't be leaks.

millions of homes with non leaking toilet drain piping, this is not something you plan on being serviceable or inspect-able.

put in a drop ceiling i suppose.

  • Yeah, that may just be the answer. I think I'm paranoid because in my lifetime, I've seen a few toilets in my homes or others' that have leaked. Nothing like a huge flood, but enough regular leaking (like around the wax ring or drain pipes) to make a spot on the ceiling below which, left unchecked, would cause mold, wreck ceilings, or worse. Water is the enemy of a home. :D But at this point, everything is professionally repaired. In theory, if it leaks again, it'll be long after we move out of the place. Not a great thought, I know... Feb 16, 2023 at 14:45

I use this leak sensor at my home. In all location where I suspect leaks.

Govee WiFi Water Sensor comes in single and up to 10 sensor package. There are other makes, but I am happy with my product. It sometimes activates, when my spouse mops the floor, and she is not happy about the very loud noise.

I have it placed on the floor near dishwasher, under the sink, near the toilets and other places.

I did it after I had a leak under the sink, so no more surprises.


  • That's cool. Looks like a perfect solution for under sinks and in the basement. I might pick up a set of these. Unfortunately, we won't have access in the ceiling to place one of these and keep the batteries fresh, so for the original question, I don't think it would work. Feb 16, 2023 at 14:37

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