Home · Cleaning · Best practice · Why window cleaners use purified water
Cleaning best practice
The short answer
Deionised water dries without spots because the dissolved minerals that leave those spots have been removed, which is why glass can be left unwiped.
Tap water leaves a mineral deposit as it evaporates. Removing the minerals first means the rinse can simply be allowed to dry.
How it is done
- Purify the water; check the meter rather than trusting the filter's age.
- Agitate with a brush, then rinse the whole pane including the frame.
- Rinse top down and let the pane dry untouched.
- Traditional squeegee work is still the better answer on internal glass.
Why it matters
In a region with mineral-rich supply, the difference between purified and tap water on a facade is visible from the ground within a day.
questions
Asked about this
Almost always tap-water minerals drying on the pane, or run-off from a dirty frame that was not rinsed.
Up to a practical height. Above that, rope access or a cradle is the correct method, and it is a permitted, certified activity.
references
Background reading
- Purified water — Wikipedia
- Window cleaner — Wikipedia
External encyclopaedia entries for the underlying concepts. They explain the science; the practice above is how we apply it in UAE properties.