Tenant has Mushrooms growing in bathroom

[James Nix]

Hey everyone,

So I got sent a picture of what seems to be mushrooms growing in the ceiling of my tenant bathroom. I sent the picture out to my contractor already waiting for feedback but I wanted to share it here also to get some feedback on what it might be & the actions that need to be taken to correct the problem.

I attached the picture so everyone can get a look at it. I appreciate any feedback or opinions given on the situation. 

[Richard F.]

Aloha,

Pretty sure sign of a leak...is there another floor above with a bathroom? or just the roof? Follow the water.