Every water heating device has a drain valve that is located at the bottom of the tank, where it is used in draining the tank and in removing the sediments. If the valve is faulty, it can actually create a pool of water at the bottom of your tank. In this case it should be replaced. Another reason for leaks can be that the valve is not tight enough, causing the water to seep at the edges. In this situation, you can simply tighten it.