If a window has white spots or drip lines that are still there after it's been cleaned, it's almost always hard water: minerals that dried on the glass so many times they bonded to it.
Where it comes from around here
- Sprinklers. A head aimed at the shrubs next to the house hits the low panes every morning. This is the usual source.
- Outdoor showers. The glass next to a beach rinse station or pool shower gets splashed every day in summer.
- Well-water irrigation. Water from a well can carry iron, which leaves orange or rust-colored spots instead of white ones.
- Runoff. Water dripping off a roof edge or a balcony above leaves a line of spots along the same pane.
Is it salt or hard water?
Salt haze is an even, cloudy film over the whole window, worst on the Gulf side, and it rinses off. Hard-water stains are spots and drip lines, usually concentrated on one wall or the low panes near a water source, and they stay after a cleaning. A window can have both.
What you can try
For light, fresh spots, diluted white vinegar left on the glass for a few minutes and then rinsed and wiped can dissolve them. Keep it off stone sills and metal. If it doesn't work after a couple of tries, the spots have set.
What to avoid
- Razor blades. They can scratch glass, especially tempered glass.
- Steel wool, scouring pads and abrasive powders. They scratch.
- Strong acids from the hardware store. They can damage frames, coatings and anything they drip on.
When it's etched
Stains left for years can eat into the glass itself. That's called etching, and it's damage, not dirt, so it can't be cleaned off. If we see it, we'll tell you before starting stain removal. Set spots that aren't etched can usually be removed by hand. That work is priced after we've seen the glass, because it depends on how heavy the spotting is.
Stopping it
Turn or lower the sprinkler head so it stops hitting the glass. That one change does more than anything else. After that, a regular cleaning with filtered water keeps new spots from getting the chance to bond.
