— Mary, California

A: Every month I get this same question, and it's funny you used the word "haunted," since your problem sounds like a case of what plumbers call a "phantom flush." This is usually caused by a small leak in the flapper seal of the toilet tank. Or, in rare cases, the flush-valve fill tube has fallen in the overflow pipe and acts as a siphon. Either way, water will slowly leak from the tank into the bowl. When the water in the tank drops to a low level, the fill valve does its job and refills the tank, causing the phantom flush sound. A quick service call from a licensed plumber should flush the ghosts from your toilet.