What Is a Toilet Dye Test?
Quick answer
Food coloring in the tank tells you in 15 minutes whether water is sneaking into the bowl.
The 15-minute diagnostic for a leaking toilet flapper: drop food coloring or a dye tablet into the tank water, wait without flushing, and check the bowl. Color reaching the bowl means water is sneaking past the flapper. The seal is done.
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