How to Remove Hard Water Spots From Windows

Hard water spots show up as cloudy white marks that don't wipe off with regular glass cleaner — and in Calgary, they're usually caused by sprinkler overspray or mineral-heavy runoff from melting snow.

Why Regular Cleaner Doesn't Work

Hard water spots are mineral deposits — calcium and lime, mostly — left behind after water evaporates. Standard glass cleaner is designed to lift dirt and oil, not dissolve minerals. That's why spraying and wiping harder just smears it around.

What Actually Removes Them

A mild acidic solution (diluted vinegar works for light spots) breaks down mineral deposits. For heavier buildup, professional-grade descaling solutions are formulated specifically for glass and won't damage the surface if used correctly.

What Can Damage Your Glass

• Abrasive scrubbers or steel wool — these scratch the glass permanently.
• Full-strength acids left on too long — can etch the surface if not rinsed properly.
• Pressure washing directly on glass — risk of cracking, especially on older windows.

Prevention Beats Removal

If sprinklers are the culprit, adjusting their angle away from windows solves the problem at the source. If it's runoff from snow, there's not much to do except clean more frequently through spring.