may include sand, anthracite, and activated carbon. Sand and anthracite are used to intercept the larger particles to be removed and activated carbon is used as the adsorbent for smaller particles, such as colloids, bacteria and viruses, in the filtering process.
Sand is the most commonly used media in the less developed countries. The depth is usually 60-70 cm and the effective size ranges from 0.6 to 0.8, but both depth and size can vary widely. Dual media, of materials of different specific weight, is used throughout the industrialised countries; it usually consists of a layer of anthracite coal over sand. The combination can take a much higher load - four or more times the old conventional load.
Material that comprises the filter element. Glass fibres and polyester fibers are examples of filter media. ("media" is the plural of "Medium." Common practice allows it to be used as the singular form and "medias" as the plural.)