I have been using DI for about 2 months now. It allows me to wash windows & screens with the pressure washer and the screens still in place. I wash with the PW and then go back and rinse with the DI. I still squeegee the window without the screen, mostly because customers expect it, it isn't really neccessary. The system ran about $500 plus new filters every 300 gallons at about $75. Hope this helps