Water around the base of the toilet

Find the source before you buy anything

Water on the floor around a toilet has four common causes, and they need four different fixes ranging from free to a full replacement. Guessing wastes an afternoon, so spend ten minutes identifying it properly.

Dry the floor and the whole toilet completely. Lay dry paper towel all the way around the base and behind it, under the supply line. Then flush once and wait a few minutes. Where the paper wets first is your answer.

Wet only after a flush, appearing under the base: the wax seal

The toilet sits on a wax ring that seals it to the drain flange in the floor. When that ring fails, each flush pushes a little water out under the base. The tell is that it is dry between flushes and wet shortly after one.

This is the serious one, not because the repair is hard but because of where the water goes. Most of it does not appear on your floor — it goes into the subfloor, and rotted subfloor and joists cost many times what the repair does. If the floor near the toilet feels soft or springy, mention that when you call, because the scope is now bigger than a seal.

It is a competent DIY job: shut off water, drain, disconnect, unbolt, lift, scrape, new ring, reset. But a wax ring that is seated slightly wrong leaks invisibly for months and you will not know until the damage is done. Most people should hand this one over, and should ask whoever does it to inspect the flange while the toilet is off.

Wet behind the toilet, all the time: the supply line

If the paper towel behind the toilet wets first, and it happens regardless of flushing, the leak is in the supply — either the braided hose, one of its two connections, or the shut-off valve on the wall.

This is the friendliest outcome on the list. Dry it, run a finger along the hose and both connections to find the exact point, and snug the connection gently — hand tight plus about a quarter turn. Do not crank it; the plastic nut on the tank side cracks easily. If the hose itself is weeping rather than the joint, replace it. A braided stainless line costs about ten dollars, and a burst one floods a house, so it is worth changing an old one on principle.

Wet between tank and bowl

Water appearing at the join where the tank meets the bowl runs down the back and pools at the base, which makes it look like a base leak. The cause is either loose tank bolts or a flattened tank-to-bowl gasket.

Shut off the supply, flush, sponge the tank dry, and snug the bolts from inside the tank — alternating sides a little at a time so it seats evenly, and stopping well short of hard. Porcelain does not forgive over-tightening. If even tightening does not stop it, the gasket needs replacing, which means lifting the tank off the bowl and is a reasonable point to call someone.

Condensation, which is not a leak at all

In humid weather, cold water in the tank chills the porcelain below the dew point and the outside of the tank sweats. The drips run down and puddle at the base, looking exactly like a leak.

The test is simple: if the outside of the tank is uniformly damp and cold to the touch, and the puddle is worst in summer or after several flushes in a row, it is condensation. An insulating tank liner or a mixing valve solves it. Nothing is broken.

If the toilet rocks

A toilet should not move at all when you sit on it or push it side to side. Rocking means the flange it bolts to has broken, corroded, or pulled out of the floor.

Do not fix a rocking toilet with shims alone. Shims stop the wobble you can feel while the flange keeps deteriorating underneath, and each rock works the wax seal a little looser — so a rocking toilet reliably becomes a leaking toilet. Check whether the closet bolts at the base are simply loose first, but if the movement is coming from the flange, that needs proper repair.