Short answer
First find the source. Dry the floor and check the supply line, the tank bolts and the outside of the tank, because water from above often ends up at the base. If water seeps out from under the toilet when you flush, the wax ring has failed. Snug the bolts at the base a little. Still leaking? Shut off the water and replace the wax ring, or call a plumber.
How to find and fix a leak at the toilet base
1A puddle around the base
Water that comes back after you dry it. Stop using this toilet for now: every flush can push dirty water under the floor.
Read all the steps
- A puddle around the base. Water that comes back after you dry it. Stop using this toilet for now: every flush can push dirty water under the floor.
- Dry it, then look above the floor. Run a paper towel along the supply line, the tank bolts and the tank. A drip from up there often ends up at the base.
- Flush and watch the base. If water seeps out from under the toilet right after a flush, the wax ring that seals it to the drain has failed.
- Snug the bolts at the base. Pop off the caps on each side. Turn each nut a quarter turn, side to side. Stop when it is snug: too tight cracks the porcelain.
- Still leaking? Replace the wax ring. Shut off the water, flush, sponge out the tank and unhook the supply line. Remove the nuts, lift the toilet straight up and set a new ring.
- Set it back and check. Lower it straight down, press evenly and snug the bolts. Reconnect, open the valve slowly and flush a few times.
- Still not fixed? Call a plumber Especially if: the floor around the toilet feels soft, or the ceiling below has a stain.
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Where the water comes from
- Only when you flush, from under the base: the wax ring.
- All the time, dripping from above: the supply line nut, the tank bolts or a cracked tank.
- Drops all over the outside of the tank on humid days: a sweating tank, not a leak.
- Water even when nobody flushes, with no drip above: a hairline crack in the bowl. The toilet needs replacing.
What not to do
- Do not caulk around the base to stop the leak. It hides the water while the floor rots underneath.
- Do not crank the bolts down hard. Cracked porcelain means a new toilet.
- Do not reuse the old wax ring, even if it looks fine. Use a new ring and new bolts.
Replacing the wax ring yourself
Plan a couple of hours and get a helper: toilets are heavy and awkward. You need a new wax ring, new bolts, a putty knife and a sponge. If the flange (the ring on the floor that the bolts attach to) is broken, or the floor feels soft, stop and call a plumber.
When to call a plumber
- The floor around the toilet feels soft, or the ceiling below has a stain.
- The flange on the floor is broken or rusted through.
- It still leaks after a new wax ring.
- You see a crack in the bowl or the tank.
Frequently asked questions
Why is my toilet leaking at the base when I flush?
Most likely the wax ring under the toilet has failed, so some water escapes on its way to the drain. Loose bolts at the base can cause it too, which is why you snug them first.
Can I just caulk around the base of the toilet?
Not to fix a leak. Caulk hides the water and the floor rots underneath. Caulk is fine once the leak is fixed, with a gap at the back so a future leak shows.
Is a toilet leaking at the base an emergency?
It is urgent, not a flood. Stop using that toilet, because the water is dirty and soaks into the floor. Fix it or call a plumber within a day or two.
How long does a toilet wax ring last?
Often as long as the toilet. It fails sooner if the toilet rocks, the bolts work loose or someone overtightens them.
Can I replace a toilet wax ring myself?
Yes, if you are handy and have help lifting. Shut off the water, empty the tank, lift the toilet straight up and use a new ring and new bolts. If the flange or the floor is damaged, call a plumber.