Pentair Pentek RFFE Filter Cartridges are designed to provide an easy and effective method of reducing dissolved iron from water, which greatly improves the taste. This cartridge helps to eliminate the orange and brown stains often found in sinks, toilets, tubs and other plumbing fixtures. It also reduces the possibility of damage to pipes and water heaters and reduces up to 3 ppm dissolved iron. It adds no harmful chemicals to the water, making it completely safe for drinking water applications. The Pentek RFFE20-BB Cartridge is designed for use in the Pentek 20-inch Big Blue Filter Housing and should be installed on the main cold water line after the pressure tank or water meter. For best results, pre-sediment and post-carbon treatment is recommended.