Most homeowners think of window cleaning as cosmetic. In Arizona that framing is wrong, and it costs people money. Hard water on glass in this climate is a progressive process with a point of no return, and once you pass it, the fix is glass replacement rather than cleaning.
The Difference Between a Spot and Etching
When mineral-heavy water lands on glass and evaporates, it leaves calcium and magnesium behind. In the early stage, that deposit sits on top of the glass. It looks like white, chalky spotting, it laughs at household cleaner, but it is a deposit on a surface and the right professional treatment removes it.
Leave it long enough and the deposit reacts with the silica in the glass itself. It stops being a layer on the surface and becomes a change in the surface. That is etching, a permanent alteration that reads as cloudiness or haze.
Etched glass cannot be cleaned. There is no product and no technique. Depending on severity it can sometimes be improved through professional glass restoration, but often the honest answer is replacement.
Sprinkler Overspray Is the Number One Cause
Rain is not your problem here. Your irrigation system is. A misaligned head that hits the bottom two feet of a window every morning delivers mineral-heavy municipal water to that glass 365 times a year, and Arizona sun bakes it dry within minutes, concentrating the minerals rather than letting them run off.
That is why the damage pattern on Valley homes is so consistent: heavy white buildup on the lower portion of ground-floor windows facing the irrigated landscaping, while the upper portion of the same window looks fine.
Go look at your windows. If you see that pattern, walk your sprinkler zones while they are running and find the head doing it. Adjusting one sprinkler head is free and it stops the clock on a problem that eventually becomes a glass replacement quote. Same applies to pool splash-out and patio misting systems.
What We Can Remove and What We Cannot
Reliably removable: desert dust and general grime, ordinary water spotting, films and streaks from DIY cleaning, buildup in frames and tracks, and most hard water deposits still sitting on the surface.
Sometimes improved: heavy long-term mineral buildup. How much comes off depends on how long it has been accumulating and how much sun that glass gets.
Not removable: true etching and physical damage to the glass.
A rough test: if the affected area feels slightly rough under your fingertip, you are likely looking at etching. If it feels smooth but looks cloudy, the deposit is more likely still on the surface.
The Parts Most Companies Skip
Tracks. Arizona window tracks fill with dust that turns into a paste every time moisture hits it. That is why sliding doors get harder to move over the years, and it means every time you open the window you pull grit back onto clean glass.
Frames. Dust on the frame washes down onto the glass on the next irrigation cycle or storm. Skip the frame and you have built in a re-soiling mechanism.
Screens. Screens hold a remarkable amount of dust in this climate and transfer it to the glass constantly. Cleaning glass while leaving dirty screens is like mopping a floor and putting the dirty mat back down.
How Often, Realistically
The variables that drive it: sprinkler overspray, which is the biggest factor and the most urgent; proximity to open desert or ongoing construction; monsoon season, which deposits a heavy layer of fine dust on every exterior surface; and how much you care about the view.
Two service points make sense for most Valley homes: after monsoon season ends in the fall, and in spring before the dust picks up. Homes with active overspray should be looked at sooner regardless of season.
Why DIY Usually Makes It Worse
Household glass cleaner is formulated for fingerprints and light grime and does essentially nothing to mineral deposits, so people escalate: harder scrubbing, abrasive pads, stronger chemistry. Abrasives micro-scratch glass, which creates more surface area for the next round of deposits to grip. Some acidic products accelerate etching rather than reversing it.
And the heat works against you. Cleaner evaporates off hot glass before you can work it, which is the actual reason DIY attempts streak. It is not technique.