Use a mixture of 50 percent vinegar and 50 percent water to remove water spots from glass. Soak a towel in this mixture, and press it into the spots on the glass. For a minute or two, leave the towel still so the vinegar's acidity softens the deposits.
After the mineral deposits soften, the spots are easier to wipe away. Another way to do this is to drape the towel in place on the glass if it's possible to secure it in place. After wiping the spots off, use a clean rag to dry the window. Spray the glass with a window cleaner before drying to produce a shinier finish.
In some areas, water has a higher mineral content than in others. When calcium and magnesium levels are high in water, the result is "hard water." Even after this water evaporates, it leaves calcium deposits, also known as lime scale, behind. Initially, this is difficult to notice, but soon a thick, white glaze builds up. If the sun bakes these deposits in, they become more difficult to clean.
Alternatively, white wine produces a similar effect to vinegar. White wine also has enough acidity to dissolve the deposits, although it is significantly more expensive by volume.