There is a dripping sound coming from my toilet. It happens about once a minute constantly. I've eliminated every possibility I could think of:
- I put food coloring into the tank and waited 20 minutes. The water in the bowl did not change color. Furthermore it does not exhibit the other sign of a leaking flapper, the tank occasionally refilling.
- I observed the refill tube and did not see anything dripping from it.
- I turned off the water and the sound continued. After leaving the water off overnight, the sound stopped.
- Unlike How to fix dripping sound coming from toilets? this happens pretty much constantly, not just when material is added to the bowl.
Any other ideas? Or problems with my beliefs above?
UPDATE: As per a comment on the accepted answer, I replaced the fill valve, and the sound went away. That was only three years ago. Now, the sound is back. Fill valves should last longer than three years, right? The new fill valve wasn't even the same brand or style as the old one.