Water filters are used to remove chemical, physical and biological contaminants from water. By removing these contaminants, water filters improve the smell, taste and safety of water used for drinking, cooking and bathing. They are also used to aid in meeting public health standards for swimming pools and irrigation water.
Filtering water goes beyond putting water through a sieve or screen to remove particles. Depending on the type of filter used and the type of contaminant to be removed, a filter can remove particles much smaller than the holes through which the water passes. For home use, point-of-use filters are the most practical. Small systems can be installed directly at faucets and other water outlets, while larger ones can treat all water coming into the house.
Finding the most effective and economical system for home use depends on the contaminants to be removed, making water testing a must prior to choosing a filter. Homes serviced by a public water utility can check the utility's yearly Commercial Confidence Report, which provides information on contaminants in the water supply and how contaminant levels compare to national standards. Homeowners with private wells should have their water tested annually in late spring, when contamination by pesticides is most likely. Then, they can choose a filter system specifically designed to remove the type of contaminants found.