I live in Texas (hard water) and I always hand wash our cars. It is something that I really enjoy. I have always wanted something to help with the hard water problems that I encounter. First off never wash your car in the sun or you will get hard water spots from the car drying before you can get the water off. This filter really cut my time in half. The filtered water actually works better with my products and the car comes clean much faster. I do not have to work on the rims multiple times to get the brake dust etc off. The water feels soft and I think this also helps the dirt to slip off the car and it probably puts a protective coating between the dirt and the paint, to stop all those love marks that appear from normal wash and wiping down a car. I am ordering more of these now. I do not know how long they last but I have washed 2 cars and I use a pressure washer as using the filter does cut down on the pressure of the water. But I have used the pressure washer on one car and just the regular hose on the other car and had great results with both.