An under sink water filter is a water filter which is designed to treat drinking water before it reaches the tap, ensuring that it will be safe to drink and free of sediments and other impurities which could negatively impact flavor. Many under sink water filters are designed to be very easy to install, eliminating the need for a plumbing professional, but it is also possible to purchase more complex water filtration systems. Home supply stores are a good source for this type of water filter, as are plumbing suppliers and specialty companies.
In a basic under sink water filter, the water filter is screwed on to the valve below the sink, so that when the water is turned on, it passes through the filter before reaching the tap. The filter has a cartridge which traps particles. Depending on the design, the filter may just grab sediment before it hits the tap, or it may trap bacteria and viruses as well. The cartridge usually needs to be periodically cleaned or replaced, as it will eventually clog with sediment.
Other under sink water filter systems involve the installation of a separate tap at the sink just for drinking water. In these cases, the sink plumbing includes a split from the cold water pipe which feeds the drinking water tap. This split goes through the water filter, so that when the drink water tap is turned on, the water is filtered as needed. Some people like the separate tap option for water filtration, while others prefer a single-tap system.
There are a number of reasons to use an under sink water filter. In older homes, there may be sediment in the pipes which causes problems with drinking water, such as rust, which creates a bad taste. Instead of replacing the pipes, which can be very expensive, an under sink water filter can be installed. This type of filter can also be used to remove chlorine and other remnants of water treatment used for municipal water, to improve the flavor of tap water.
People who rely on their own wells or water collection systems for drinking water may choose to use an under sink water filter to improve the safety of their water supply. In these instances, the water may be perfectly fine to use for washing, bathing, and cooking, but it might be dangerous or unpleasant to drink. Using an under sink water filter is cheaper than using a whole house water filter, and more convenient than filtering water in a special pitcher or jug.