Hard water stains on glass and shower doors are often mistaken for soap scum. Unfortunately, soap scum removers will not remove hard water stains. The high concentrate in hard water of dissolved minerals such as calcium and magnesium are not something that can be sprayed away with your average cleaner. Hard water actually makes your favourite cleaners less effective. You need to attack the hard water stains with acid-based cleaners. You can try to clean the stains naturally without using harsh chemicals by using vinegar and baking soda. If you are lucky this will solve the problem. If not, low-odour hob cleaners such as Weimans cooktop cleaner will remove the hard water build-up.
Combine a paste of vinegar and baking soda. This natural solution is the cheapest formula to remove hard water stains from glass.
Apply the paste to the hard water stains using a scrubbing sponge in a circular motion. Work the hard water stain while applying this paste and allow it to sit for 15 minutes.
Wipe off the paste with a damp towel and remove excess water with a squeegee. If you are lucky your hard water stains will be removed. If your stains have been sitting for several years you may need to further clean your glass.
Apply a cream hob cleaner to the remaining hard water stains in a circular motion with a scrubbing sponge. Allow the hob cleaner to dry for 15 minutes.
Buff the dried hob cleaner with a towel. Your glass will now be free of hard water deposits. You will need to repeat this process once every six months to keep your glass free of hard water build-up.
After cleaning, apply Rain-X to prevent hard water build-up. Shower doors should be wiped dry after each use to prevent build-up.
Do not use sandpaper to try to remove hard water stains. This may scratch the surface of the glass, ruining it.