A water filter removes impurities from water by means of a fine physical barrier, a chemical process or a biological process. Filters cleanse water to different extents for purposes like irrigation, drinking water, aquariums, ponds and swimming pools.

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Point-of-use filters 

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Point-of-use filters for home use include granular-activated carbon filters (GAC) used for carbon filtering, 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 buildup. 

Point-of-use microfiltration devices can be directly installed at water outlets (faucets, showers) in order to protect users against Legionella spp., Pseudomonas spp.,Nontuberculous mycobacteria, Escherichia coli and other potentially harmful water pathogens by providing a barrier to them and/or minimizing patient exposure.