Purified water is water that’s free from any impurities. Impurities commonly found in ordinary tap water are minerals such as Calcium, Magnesium, Sodium, Potassium and Phosphorus. These minerals are perfectly safe to drink, however when it comes to window cleaning and car detailing they are not ideal due to how they dry. When non-purified water dries, the minerals become visible, leaving spot marks on the surface. This obviously doesn't look good and also means the windows will get dirty again quicker, as impurities from rain water and dust etc, are more likely to cling on to the window if its covered in impurities.
In order to create pure water, specialised filtration systems are used which aim to remove every single mineral, leaving the water 100% purified. Pure water is measured by TDS (total dissolved solids) PPM (parts per million). Average tap water measures somewhere between 180 – 320 PPM, and ultra-pure water should measure at zero PPM or below.
Once the water has been purified it can then be used for many purposes, the cleaning industry being the biggest, which includes window cleaning & car detailing. There is also a high demand for purified water with aquarium fish tanks, as special fish species need pure water to help them live in a natural habitat. You can read more about Using Spotless Water for Aquarium Fish Tanks here.