How to Remove Hard Water Stains From a Glass Shower Door

What hard water stains actually are

Those cloudy white spots aren't soap alone. They're minerals. The USGS Water Science School explains that water hardness comes mostly from dissolved calcium and magnesium. When shower water dries on glass, the minerals stay behind. The USGS scale:

Hardness (mg/L as calcium carbonate)	Classification
0 to 60	Soft
61 to 120	Moderately hard
121 to 180	Hard
More than 180	Very hard

If your water falls in the hard or very hard range, expect spots to build up quickly. Soap combines with the minerals, too. University of Nebraska-Lincoln Extension says hard water increases films and stains from soaps and minerals, and that surfaces in contact with it need more frequent cleaning.

Why vinegar works

Acids loosen mineral scale. UNL Extension says household vinegar is about 4 to 8 percent acetic acid and may remove hard water deposits from glassware. Lemon juice, which contains citric acid, works much the same way. A University of Idaho Extension guide to household cleaning products also lists vinegar as a very mild acid that removes hard water deposits.

Glass makers recommend the same approach. The Pilkington OptiShower cleaning guidelines, written for coated shower glass, call for a 50/50 solution of water and white vinegar, or 80/20 water and citric acid, for routine cleaning in hard water areas. They suggest a vinegar-based cleaner for deep cleaning.

Step by step

You'll need white vinegar, a spray bottle, a soft sponge or microfiber cloth, a squeegee and an old towel.

1. Test first. Delta Shower Doors says to try any cleaning product on a small, inconspicuous area before using it on the whole door.
2. Protect the frame and hardware. Lay a towel along the bottom track and cover metal handles. Sterling's care guide says never to use cleaners containing acids, ammonia, bleach or abrasives on metal surfaces, because they can damage the finish.
3. Spray the glass with a 50/50 mix of white vinegar and water.
4. Let it sit a few minutes, then wipe in circles with a soft sponge or microfiber cloth. Don't leave it to dry on the glass; Sterling advises against letting cleaners sit on the surface.
5. Rinse with clean water and squeegee from top to bottom, then wipe the edges dry.
6. Repeat for heavy buildup. If a haze remains, try the 80/20 water and citric acid mix that Pilkington lists, or a store-bought vinegar-based glass cleaner.

What not to use

• Razor blades, scrapers and steel wool. Pilkington warns these can damage the glass surface and its coating, just as with normal glass. Sterling says never to use sharp instruments on its glass panels.
• Gritty cleansers and scouring pads. Delta says not to use abrasive cleaners, bristly brushes or rough sponges. UNL Extension notes that coarse abrasives damage glass, and scratched surfaces get dirty faster.
• Acid on the frame. Vinegar is fine on the glass, but Sterling says acids can damage the finish on metal parts. Keep it on the glass and rinse any drips off the frame.

If your door has a protective coating

Many doors come with a factory coating that makes water bead off. Sterling treats its frameless doors with CleanCoat and says abrasive cleaners aren't recommended on that glass. Delta's Spot Guard is a hydrophobic coating on the inside panels. Check your door maker's care page before using anything stronger than diluted vinegar.

Keep spots from coming back

Prevention takes less than a minute per shower:

• Squeegee after every shower. Delta says to do this after each use and wipe the door dry with a soft microfiber cloth, especially if you have hard water.
• Wipe the door dry. Sterling says drying the door after each use helps avoid soap deposits and lime buildup in hard water areas.
• Leave the door open so the enclosure dries and air circulates, as Sterling suggests.
• Do a quick vinegar wipe weekly if your water is very hard, so the minerals never set.

If hard water is also leaving residue in your laundry, our guide to why laundry smells after washing covers what builds up in the washer.