The 3M Whole House Water Treatment Media is calcite, a calcium carbonate filter media used to neutralize acidic or low pH water to a neutral, less corrosive effluent level in residential and commercial applications. Calcite is a naturally occurring calcium carbonate media. One of the advantages of the Calcite media is its self-limiting properties, meaning that when used properly for acid neutralization and pH correction, it corrects the pH levels only enough to reach a non-corrosive state. This pH corrected state helps prevent the potential of leaching of copper, lead and other metals found in typical plumbing systems. When used in a 3M water treatment system, such as a backwash filter, the periodic backwashing prevents packing of the media bed and maintain high service levels of the media. Calcite media needs to be replenished periodically as the Calcite depletes. This replenishment rate depends on many factors including pH levels, backwash frequency and filter system capacity.