What is the water we use to clean your windows? It's not the normal water you receive from your tap as this would leave water marks when it dries on the glass. We use Reverse osmosis (RO) treated water. Reverse Osmosis is a water purification process that uses a partially permeable membrane to separate ions, unwanted molecules and larger particles from tap water.
Once the water has been treated in this way it is treated again using deionization, basically filtered through a resin. Deionized water (DI water) has almost all of its mineral ions removed,like sodium, calcium, iron, and copper, and anions such as chloride and sulfate. Deionization is a chemical process that uses ion-exchange-resins, Ion-exchange resins are widely used in different separation, purification, and decontamination processes.
We use deionization for the final polish of our already reverse osmosis treated water to bring the final PPM (parts per million) of the water down even more. Now when it dries on your window it will leave no residue whatsoever, leaving them looking shiny and clean.