How to remove hard water stains from glass?
Depending on how advanced the hard water is on the window, a variety of techniques can be used. Start by using your fingernail and if you can feel the buildup. If the surface is smooth, you may be able to use steel wool. Make sure the steel wool is wet and use some elbow grease. If this does not work, the next step is to use a less harsh method to the window by using Sorbo powder, which can be found at a janitorial supply store. Apply the powder to the window with a wet scrubbing agent that will not damage the window like a white pad. If this does not work, an acidic compound will need to be used. Only let professionals perform this process. One can damage the window or other components of the window very easily if not used properly.