You had a rough surprise. A shower head was left spraying the bathroom floor. It ran for a few minutes. Water then showed up in the living room below. It pooled on the drywall ceiling. It even drained through a light fixture.
After you shut off power and water, you open the ceiling. You did a smart test. You poured a small amount of water on the bathroom floor. From below, you saw water running down the outside of the toilet drain pipe.
You are in Quebec. A local plumber said this is normal. He said no repair is required by code. Your toilet flushes fine. You see no leak during normal use.
Why can this happen
A toilet drain is a big hole in the floor. The flange sits in that hole. The toilet base sits over the flange. If water spills on the floor, it can slip under the toilet. It can then reach the flange opening.
Many toilets are not caulked all the way around. A small gap is often left. That gap can help show a real leak later. But it also lets spilled water get under the toilet.
Also, many bathroom floors are not truly waterproof. Tile and grout are not waterproof. Water can pass through cracks. It can also run along seams at the toilet base.
What should you do now?
- Dry the ceiling space fast. Use fans and a dehumidifier.
- Check for soft drywall and swollen trim.
- Look for staining over the next two weeks.
- Inspect the toilet for rocking. A rocking toilet breaks seals.
Should you reset the toilet?
If the toilet rocked during the spill, reset it. Use a new seal. Wax rings can leak if disturbed. A wax-free seal can also work. Choose a quality brand.
If the toilet is solid, you may not need a reset. But you can still prevent repeats.
How to prevent the next ceiling leak
- Seal the floor-to-toilet joint with caulk. Leave a small gap at the back.
- Install a shower spray guard or point the head inward.
- Use a bath mat that does not funnel water to the toilet.
- Consider a leak alarm near the toilet and shower.
Question and answer
Q: Is it normal for spilled water to leak under a toilet and down below?
A: Yes. It can happen if water gets under the toilet base and reaches the flange opening. It is common in non-waterproof floors.
Helpful external resources
- InterNACHI: how toilet wax rings work.
- CMHC: home moisture and maintenance basics.
- This Old House: toilet leak checks and fixes.
Bottom line: your plumber may be right about code. But your concern is still valid. A small spill can cause damage. Dry everything now. Then add a simple prevention at the toilet base.
I’m Chris Mayer, writing for Plumbing 101.