The windows on my LG start to fog up just a bit when the humidity is high, but the house humidity is really low. If you live somewhere with pretty good humidity int he air, you may only need to fill the water troughs provided. If you live in a more desert-like area, you probably want to add a soaking wet sponge in a bowl, or someone said they put socks in a bowl of water--more surface space to release water into the air, and when you're done, you can just toss the socks in the wash.