Ceiling stain below an upstairs toilet

Symptoms

• Brown or yellow stain forming on the ceiling below the bathroom
• Stain grows or gets darker after the upstairs toilet is used
• Ceiling paint bubbling or sagging slightly
• Musty smell in the room below

Likely causes

• CommonFailed wax ring seal upstairsWater leaking from the base of the toilet above seeps through the subfloor and shows up as a ceiling stain below.
• PossibleLeaking supply line or shutoff valveA slow drip at the connection point can travel along framing before showing up as a stain.
• PossibleCondensation dripping consistently over timeA chronically sweating tank can, over months, contribute to enough moisture to stain a ceiling below.
• PossibleUnrelated plumbing leak in the wall or floorA supply or drain pipe leak elsewhere in that wall could be the actual source, not the toilet itself.

What to do

1. Check the upstairs toilet for rocking, base leaks, or supply line moisture as described in the base-leak guide.
2. Turn off water to that toilet temporarily if you suspect it and see whether the stain stops growing over the next few days.
3. Avoid using the affected room heavily and consider placing a container to catch any active dripping.
4. Take photos of the stain's size now so you can track whether it's spreading.
5. Have the source confirmed and repaired promptly, since ceiling water damage gets more expensive to fix the longer it continues.

Tools and parts

• Flashlight
• Camera or phone (to track stain size)

When to call a pro

Call a plumber to confirm and fix the leak source, and a contractor if the ceiling material itself needs repair after the leak is stopped.

Safety