Hard water stains on windows can be treated with a 50/50 mixture of white vinegar and water. Spray the solution directly onto the stains and let it sit for about 10 minutes. Scrub gently with a non-abrasive cloth or sponge, then rinse with water. For extra cleaning power, use a baking soda paste or a commercial hard water stain remover. Repeat the process for tough stains and dry the windows afterward to avoid streaks.

The best way to remove hard water stains from windows is with a solution of vinegar and water. Let it soak for several minutes, then scrub with a cloth. Baking soda paste or a commercial cleaner may be necessary for particularly stubborn stains. Ensure windows are dried properly to avoid streaking.