Quick answer
A standard tap-water wash typically looks great for about a month before mineral film and dust dull it. A pure-water clean stays clear up to ~6× longer — often several months — because it leaves no mineral residue for dust to cling to. How long yours lasts depends on weather, location, sprinklers and trees.
Why pure water lasts longer
The secret isn’t magic — it’s chemistry. A tap-water wash dries leaving a faint mineral film (Calgary’s hard water), and that film grabs dust and shows spots quickly. Pure water leaves nothing behind, so there’s no film and nothing for dust to stick to — the glass simply stays clearer, longer.
What shortens the time between cleans
- Sprinkler overspray — hard water on the glass spots fast.
- Busy roads/construction — extra dust and exhaust.
- Lots of trees — pollen, sap and birds.
- Storms and wind-driven dust after a clean.
How to make a clean last
- Choose a pure-water clean over DIY tap-water washing.
- Adjust sprinklers so they don’t hit the glass.
- Clean screens too, so they don’t re-soil the glass.
- Stick to a regular schedule — spring and fall for most homes.
Keep it clear year-round
Book a recurring spring + fall schedule and your glass stays consistently clear. Get a free quote.
Frequently asked questions
How long does professional window cleaning last?
A pure-water clean stays clear up to about 6× longer than a tap-water wash — often several months — because it leaves no mineral film for dust to cling to. A standard wash usually dulls within a month.
What makes a window cleaning last longer?
A pure-water (0 TDS) rinse, plus keeping sprinklers off the glass, cleaning screens, and sticking to a regular spring/fall schedule.
Why do my windows get dirty so fast?
Sprinkler overspray, busy roads, construction dust and nearby trees all speed up soiling — and a tap-water wash leaves a mineral film that attracts dust quickly.
