Filters

A water filter removes impurities by lowering contamination of water using a fine physical barrier, a chemical process, or a biological process. Filters cleanse water to different extents for purposes such as providing agricultural irrigation, accessible drinking water, public and private aquariums, and the safe use of ponds and swimming pools.

Types of water filters include media filters, screen filters, disk filters, slow sand filter beds, rapid sand filters, cloth filters, and biological filters such as algae scrubbers.

Point-of-use filters for home use include granular-activated carbon filters (GAC) used for carbon filtering, depth filter, metallic alloy filters, microporous ceramic filters, carbon block resin (CBR), microfiltration and ultrafiltration membranes. Some filters use more than one filtration method. An example of this is a multi-barrier system. Jug filters can be used for small quantities of drinking water. Some kettles have built-in filters, primarily to reduce limescale build-up. Standard Flowmatic cartridge style filters are added to existing plumbing; the filter cartridges are cylinders 10 inches (254 mm) long by 2.5 inches (64 mm) in diameter. They are made by multiple manufactures and are available in 0.5-100 micron ratings as well as activated carbon. Some common substances that filtration does not remove are arsenic, bacteria, chlorides, fluoride, nitrates, perechlorates, pharmaceuticals, sodium and viruses