Many toilets have slow, silent leaks. As the tank’s water level drops, the toilet will briefly run to replace lost water. This may be very quick, quiet, or even silent.
How to check for toilet leaks with a dye-test:
Visit ToiletFlapper.org for a video tutorial on how to do a dye-test.
Did you know? A poorly sealing flapper can waste as much as 200 gallons of water per day.