If the faucet still leaks after you've replaced the washer, you probably have never heard of the washer's better half -- the valve seat. This oft neglected fellow is located below the stem and can be accessed when the stem is removed. Without a valve seat even the best washer is useless. They work together to form a watertight seal. When one or both breaks down, you get leaks. And here's more bad news. You're going to need a special wrench, (which you may use once in your lifetime), to get it out. It never ends.