Have you noticed a stream of water flowing down a window in your Michigan home whenever it rains? Maybe there have been some drops of moisture along the sill or a little water between the sash and the frame. A window leak should never be ignored. Not only can the water that seeps in damage your building materials and contribute to mold growth, but if there's water leaking in, there's probably air leaking in, too. And that's bad news for the energy bills in your Michigan home.