What occurs during a "spot-free rinse"?

During a "spot-free rinse," purified water is used to ensure that no mineral deposits are left on the vehicle's surface after washing. Traditional tap water contains various minerals and contaminants that can leave spots or streaks as it dries. By using purified water—often deionized or reverse osmosis water—these minerals are removed, resulting in a clear, streak-free finish. The purification process effectively eliminates impurities that could cause spotting, making the rinse particularly important for achieving a flawless appearance on the vehicle’s exterior. This is why the use of purified water is integral to the concept of a spot-free rinse.