Water that appears at the base of the toilet after flushing usually means the wax ring seal has failed, often because the toilet rocks or the bolts are loose. Before blaming the wax ring, rule out condensation on the tank, a dripping supply line or shutoff valve, and a cracked tank or bowl. A leaking wax ring should be replaced soon, because every flush can soak the subfloor and the ceiling below.
A little water around the base of the toilet is easy to mop up and forget. But if it’s coming from under the toilet, it’s also soaking into the subfloor every time someone flushes, and in a two-story home it can end up in the ceiling below. Here’s how to find out where the water is really coming from, what to fix, and how to check for damage you can’t see.
First: where is the water coming from?
Dry the toilet and the floor completely, then watch.
| When it’s wet | Likely cause |
|---|---|
| Right after flushing, from under the base | Failed wax ring or a loose toilet |
| Water beads all over the tank in humid weather | Condensation (“sweating” tank) |
| Drip at the wall, under the tank | Supply line or shutoff valve |
| Drips from under the tank at the bolts | Tank bolts or tank-to-bowl gasket |
| Slow seep even when not flushed | Crack in the tank or bowl |
Tip: put a few drops of food coloring in the tank. If colored water shows up on the floor, the leak is from the tank or bolts. If the water is clear after flushing, look at the wax ring.
The wax ring: most common cause
The wax ring seals the toilet to the drain flange in the floor. It fails when:
- The toilet rocks, because the bolts loosened or the floor is uneven, and the rocking breaks the seal
- The ring is old and has dried out or compressed
- The toilet was reset without a new ring
- The flange is broken, loose or too low below the finished floor
Signs of a wax ring leak:
- Water at the base after flushing
- A toilet that rocks or shifts
- A sewer smell in the bathroom
- Soft floor, loose tile or stained vinyl around the toilet
- A stain on the ceiling below the bathroom
Fixing it
- Tighten the closet bolts gently if the toilet rocks. Overtightening can crack the porcelain.
- If water still appears after flushing, replace the wax ring: shut off the water, flush and sponge the bowl and tank dry, disconnect the supply, remove the toilet, scrape off the old wax, check the flange, set a new ring and reset the toilet.
- Repair or replace a damaged flange before setting the new ring. A new ring on a broken flange will leak again.
- Replace the supply line if it drips or is old, with a new braided line, and check the shutoff valve.
Don’t just run a bead of caulk around a leaking toilet to stop the water showing. That hides the leak; it doesn’t fix it.
Check for hidden damage
A wax ring leak often runs for months before anyone notices, and it’s dirty water. Once the toilet is off:
- Look at the subfloor around the flange. Dark, soft or crumbling wood needs repair before the toilet goes back.
- Check the ceiling below the bathroom for stains, sagging or soft drywall.
- Check the basement or crawl space under the bathroom for wet joists or insulation.
If you can’t see how far the water went, hidden water leak detection with moisture mapping and a thermal camera shows the wet area under the floor and in the ceiling below, so only the damaged section is opened. For ceiling stains, see water leaking from the ceiling.
When the leak isn’t the toilet
If the floor near the toilet stays wet after you’ve replaced the wax ring, look at the neighbors: a shower pan or tub drain often leaks toward the toilet, and water from a leaking shower can show up at the toilet base. See shower pan leak. A supply line leak inside the wall behind the toilet can also run down to the floor.
And if the toilet makes a running sound or the tank refills by itself, that’s a different leak, inside the tank, that wastes water down the drain. See hear water running when nothing is on.
Get it checked
We find hidden leaks around toilets, showers and tubs across Bargersville and Johnson County, including Greenwood, Franklin and Whiteland. If the floor is soft or the ceiling below is stained, call us to map the moisture before the repair.
Still can’t find it?
Our hidden water leak detection pinpoints the leak without tearing things up, so the repair starts in the right spot.
Frequently asked questions
Why is my toilet leaking at the base?
The most common cause is a failed wax ring, the seal between the toilet and the drain flange. Other causes are condensation dripping from the tank, a leaking supply line or shutoff valve, loose tank bolts, or a crack in the tank or bowl.
Is a toilet leaking at the base an emergency?
Not usually a flood, but don't wait. Each flush can push dirty water under the toilet into the subfloor. Stop using that toilet until it's fixed if water appears after flushing.
Can I just caulk around a leaking toilet?
No. Caulk around the base doesn't fix a failed wax ring. It can hide the leak, so water spreads under the floor where you can't see it. Replace the seal instead.
How do I know if the floor under my toilet is damaged?
Signs include a soft or spongy floor around the toilet, a toilet that rocks, loose or stained tiles or vinyl, a musty or sewer smell, and a stain on the ceiling below. A moisture meter or thermal camera shows how far the water has spread.