"Watermarks", despite their name, are not really made by the water itself. It's the impurities that are found in most water that leave the marks behind. Water is made up of just two gases - hydrogen and oxygen - in the famous chemical formula H2O. When water evaporates, it returns to these two gases and disappears completely, but if there were any impurities in the water, they get left behind causing the so-called "watermarks". The water we use is 100% pure, and when we finish cleaning your windows we thoroughly rinse them with this water so that there are no other impurities left on the glass. After our water has evaporated from your windows, it leaves nothing behind but a sparkle!
