Granular Activated Carbon (GAC) filters remove volatile organic chemicals (VOC), pesticides and herbicides, trihalomethane compounds, radon, solvents and hundreds of other man-made chemicals found in tap water. 

According to the North Carolina Cooperative Extension Service, drinking water containing high levels of volatile organic compounds (VOCs) may be harmful to human health.  VOCs are a class of chemicals that have important properties in common: They evaporate or vaporize readily (they are volatile), and they contain carbon (and are therefore called organic). When present in water at low concentrations, some VOCs produce a sweet, pleasant odor.

The U.S. Environmental Protection Agency (EPA) estimates that VOCs are present in one-fifth of the nation's water supplies. They can enter ground water from a variety of sources. Benzene, for example, may enter ground water from gasoline or oil spills on the ground surface or from leaking underground fuel tanks. Other examples of commonly detected VOCs are dichloromethane (methylene chloride), an industrial solvent; trichloroethylene, used in septic system cleaners; and tetrachloroethylene (perchloroethylene), used in the dry-cleaning industry.
Volatile organic compounds may have a variety of harmful health effects. At high levels of exposure, many VOCs can cause central nervous system depression (drowsiness, stupor). All can be irritating upon contact with the skin, or to the mucous membranes if inhaled.

Drinking water containing one or more VOCs at levels above standards should not be consumed. VOCs may also enter the body through skin absorption or through inhalation of water vapor.  In addition, because little is known about the additive effects of these chemicals, special attention should be paid to detecting and eliminating VOC sources if two or more chemicals are found in water. In any case, sources of VOC contamination should be eliminated if possible.  

Filters can be installed for point-of-use (POU) treatment at the faucet or point-of-entry (POE) treatment where water enters the home. POE treatment systems are recommended for VOC removal to ensure that all water used for drinking, cooking, cleaning, and bathing is free of contamination.

Granular activated carbon (GAC) filters are typically used to reduce VOC levels in home drinking water. The effectiveness of carbon filters is related to (1) the type and amount of contaminant, (2) the rate of water usage, and (3) the type of carbon being used. Large contaminant concentrations and high water use rates reduce the carbon life. Manufacturer's guidelines for replacing carbon filters should be followed. Water entering and leaving the filter should be tested periodically to ensure that the treatment system is working properly.

Bacteria may grow on the surface of a carbon filter. It is recommended that water be disinfected after it passes through the filter to ensure its safety. Many types of disinfection systems are available. Ultraviolet (UV) light disinfection is one type of system shown to work effectively and efficiently to eliminate bacteria problems in water.
Sediment Filtration and KDF Filtration can be used in combination with GAC filtration for a comprehensive filtration approach.