Gravity-tank flush valves initiate flushing by lifting the flapper to release water from the tank into the bowl. These valve assemblies also allow water to pass through their overflow tube to refill the bowl. They're used as replacements for valves that no longer activate flushing.,Gravity-tank repair parts help fix leaks and restore proper flushing on gravity-flush toilets to avoid the expense of replacing the entire toilet. These toilet tank parts are used to replace broken or worn parts on gravity-fed tanks commonly found in homes, multifamily residences, hotel rooms, and other low-traffic settings (20 to 30 flushes per day). Signs that a toilet tank needs repair include leaking, constant running, and failure to flush.