Water purification is a process where undesirable chemicals, materials, and biological components are removed from the water. Water is purified for a specific purpose. It could be for water consumption by humans, medical uses, and industrial applications. For example, if you want to remove ions or dissolved substances in the water, you must use a reverse osmosis water filter.

Removing these dissolved substances is quite a complex process. The water must first be pre-treaded in a reverse osmosis unit to remove non-ionic organic contaminants. Then the water goes through electrodeionization, where water is passed between a positive and a negative electrode. Complete removal of ions in the water is called electrodialysis, after which the water can be used for food processing, seawater desalination, or glycerin purification.