apologies if this is a super basic question, but this is my first time owning a home and not sure who to call.

So my boiler seems to be leaking -- I think this may have been happening for a while, but the problem is that my bedroom is right next to the boiler. I'm worried, based on the white circular pattern (mold? sediment?) where water has been presumably pooling (1), if water might have intruded into the adjacent wall space and under my carpet through the slab, and who knows where else, and caused mold growth.

What is the process for stuff like this? Should I just call a general contractor to fix the boiler and possible water damage for the wood underneath? But I don't know if they would be very thorough about any mold growth... should I call a mold inspector before, afterwards, or even during? (Maybe I am being a bit crazy about the mold, I am kind of sensitive to air quality though as I have sinus issues...)    water and white stuff

source of leak

wood support

  • 8
    That appears to be a water heater rather than a boiler.
    – Ecnerwal
    Dec 3, 2023 at 4:17
  • 3
    Heads up: most people worry way more about mold than it actually deserves. This looks like a little leak. Unless it's been going for a very long time, all you need is the water heater replaced.
    – KMJ
    Dec 3, 2023 at 4:29
  • If you are very worried you can get a mold home test kit. Might put your mind at rest and should be reasonably cheap. Dec 4, 2023 at 11:38

1 Answer 1


You call a plumber and get the water heater replaced. Most of the white junk appears to be mineral build-up from ignoring a leak for a long time.

Have the new one installed properly to code with a drain pan. Not like this one was, with no drain pan evident.

If you want to rip the house apart on the possible suspicion that there could be mold, you'll need someone other than a plumber, too. Presumably a mold remediation specialist if you're particularly paranoid about it. I'd suggest fixing the leak and keeping an eye out for actual signs of a further problem before ripping the house apart, but it's your house.

  • 1
    Check how damp the area surrounding is. If it is relatively dry, then it would be a surprise to find a substantial amount of mould. But you might also want to check how solid the remaining board is. If it really has been leaking persistently, then that would cause the board to degrade, and that might have become a structural issue. You can check by comparing the feel of solid board elsewhere on the floor — stab it with a small flat blade screwdriver. Dec 4, 2023 at 17:16

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.