Are Carbon Filters Really Better for Water Treatment?
Whether you’re investing in a new water treatment system or seeking ways to boost the effectiveness of an existing one, it’s likely you’ve noticed the widespread use of activated carbon filters in water filtration and treatment systems. Are carbon filters really better?
The practice of using carbon as a filter dates to the Egyptians, who added charcoal to stored water to improve its taste and appearance. Thanks to advanced science and technology, this time-tested strategy has been significantly improved.
What is activated carbon?
Activated carbon can be produced from a wide variety of organic materials (coal, coconut shells, lignite, nut shells, peat and wood), but in the US coal is often the preferred base. The coal is heated in a furnace under controlled temperatures to enhance carbon formation, creating a complex network of pores on the surface and interior that help capture and absorb contaminants as water percolates through the material. This complex, irregular structure means one pound of granulated activated carbon (GAC) has a filtration surface area roughly equivalent to 125 acres.
How does it work?
In simple terms, carbon functions in two ways: adhesion and chemical reaction. In adhesion mode, carbon works at a molecular level, attracting waterborne compounds so they adhere to the carbonized material and are extracted from the water. In chemical reaction mode, carbon naturally interacts with specific compounds such as chlorine and converts them into something benign such as chloride.
What does it do?
Carbon effectively filters a wide range of contaminants, and in many instances, activated carbon filtration is the only or preferred treatment recommended by the EPA. While each type has its own performance parameters, activated carbon filters generally remove or reduce:
- Chemical contaminants such as benzene, trichloroethylene and vinyl chloride.
- Pesticides such as chlordane.
- Herbicides such as atrazine.
- Disinfection chemicals such as chlorine and chloramines.
- Heavy metals such as mercury.
What doesn’t it do?
On their own, granulated activated carbon filters aren’t effective against most organic contaminants such as bacteria, giardia and cryptosporidium. They also can’t remove lead, asbestos and radionuclides such as radon, nor are they particularly effective against fluoride, nitrates and sodium.
The bottom line
To boost effectiveness, carbon is often formed into dense blocks or combined with other technologies and filtering media to enhance performance and remove coliform bacteria, giardia and cryptosporidium and compounds such as lead and radon. In combination with treatment technologies such as reverse osmosis or distillation, advanced carbon filters remain one of the best filtration methods available today.