What Is the Overflow Tube in a Toilet?
Quick answer
The tank's built-in emergency drain, so water never spills onto the bathroom floor.
The open vertical tube in the middle of a toilet tank that drains excess water into the bowl if the fill valve overfills. It's the tank's failsafe: if water is trickling into its open top, the water level is set too high or the fill valve is failing.
Fixes that use this
Bathroom
How to Fix a Running Toilet in 15 Minutes (No Plumber)
A running toilet is almost always a worn flapper or a misadjusted float. Diagnose it with a dye test and fix it yourself for under $12.
Time15–30 min Cost$5–$18 easy
Bathroom
Why Your Toilet Refills Randomly, and How to Stop It
A toilet that refills on its own is leaking tank water into the bowl. Run a dye test, fix the flapper or water level, and stop the phantom flush.
Time10–20 min Cost$0–$15 easy