Pure water cleaning is water run through a purification system, either a DI (Deionized) or RO (Reverse Osmosis) system or a multi stage system using both DI and RO. Both are effective and use no chemicals. The purified water is run through a carbon fiber pole and a nylon or boar hair brush. The brush scrubs away dirt and the water leaves a spot free rinse on the glass. This method has become very popular in the window cleaning community as it is very effective for cleaning high hard to reach windows without using a ladder and cleans the windows without leaving any streaks or spots. If you prefer this method over conventional window cleaning let your local window cleaner know at the time of service.