Iron can occur in water in a number of different forms. The type of iron present is a big factor when selecting the proper water treatment system. Water that comes out of the faucet clear, but turns red or brown after time is “ferrous” iron, commonly referred to as “clear-water” iron. This color change takes place because of a chemical reaction called oxidation. When exposed to oxygen the ferrous iron dissolved in the water transforms into a ferric or rust-like partial which is red in color. Water which is red or yellow when first drawn has already “ferric” iron, often referred to as “red- water” iron. In a more rare condition iron can form compounds with naturally occurring acids, and exist as “colloidal” iron which can be very challenging to remove. Water containing iron related bacteria is said to contain “bacterial” iron. While this is not a pathogenic or harmful bacteria it often requires extra steps to remove.