A hissing sound can mean that the refill valve is still letting a tiny bit of water into the tank because it hasn’t shut off like it’s designed to. The valve shuts off automatically based on the water level in the tank. A faulty valve or one not set properly will keep running.
Does a hissing toilet waste water?
Related Articles. Toilets make all kinds of strange noises, from gurgling to screaming, and most are related to the movement of water or air. If the sound you hear from your toilet is hissing, it probably means that air or water is leaking from the fill valve.
