Many toilets eventually develop one of several problems that allow water to run from the tank into the bowl. The result is an annoying, nonstop trickling sound that wastes gallons of water each day. Usually, adjusting the refill tube or lengthening the chain connected to the flush handle stops the flow. If neither does, the culprit is the large drain hole at the bottom of the tank that's fitted with a metal or plastic ring, also known as the valve seat. The cone-shaped flapper valve fits into the valve seat to stop the flow of water out of the tank. Over time, sediment and hard-water deposits can collect on the valve seat and prevent the flapper from forming a watertight seal. The solution: Raise the flapper and scrub the valve seat clean with a piece of emery cloth or fine-grade steel.