A rocking toilet and the seal under it
A toilet that rocks or leaves water around its base has a failed seal or flange.
Updated · 3 min read
The quick version
A toilet that rocks breaks its wax seal, and that lets water and sewer gas escape at the floor. Pull the toilet, inspect the flange, replace the wax ring, shim the base level, and reset it with new bolts.
Why a rocking toilet matters
The wax ring seals the toilet horn to the floor flange. When the bowl rocks, the wax squeezes out of shape and the seal opens.
At first you might only notice a faint smell. Later, water from each flush seeps under the base and into the subfloor.
Checking the flange
Half of San Gabriel's homes were built in 1957 or earlier, and in bathrooms that age the flange is often cast iron set into the floor. After decades of mopping and small leaks, some are rusted or cracked.
A cracked flange cannot hold bolts tight. Repair rings and spanner flanges fit over the old one without cutting the pipe.
Resetting the toilet
The water is turned off and the tank drained, the bolts are removed, and the toilet is lifted out. The old wax is scraped off and the flange checked.
A new ring goes on, sometimes a waxless foam seal or a thicker ring if new tile raised the floor. The toilet is set straight down, shimmed level, and bolted.
Questions we hear
Can I just tighten the bolts to stop the rocking?
Tightening can help if done right away, but once the wax has moved, the seal is already compromised.
How do I know if the subfloor is damaged?
Soft, spongy floor near the base or dark stains below in a crawlspace point to water damage.
Is a waxless seal better than wax?
Foam seals are cleaner and tolerate a little movement. Wax still works well on a solid, level floor.