Large Capacity & Whole House Carbon Water Filters

Function

• Activated carbon is basically carbon-rich raw material such as coal or coconut shell that has been heat-treated at high temperatures. The result is a granular or porous material with a remarkably large surface area. The kind made from coconut shell tends to be more expensive. When water flows through this activated carbon, various impurities can become adsorbed or stuck to the positively charged surface of the carbon.

Types

• A whole-house or large-capacity activated carbon filter is a larger version of the pour-through carbon filters you see at many supermarkets. You can purchase several kinds of filters: granular (GAC), activated carbon block and catalytic carbon. Activated carbon block has a larger surface area and tends to remove a larger amount of contaminant. Catalytic carbon, on the other hand, is specially designed to maximize removal of compounds called trihalomethanes from the water.

Features

• Whole-house activated carbon units generally have two canisters about 4 feet tall or so; the water flows first through the one and then through the other, and sampling ports check the water after it exits both filters. These large-volume systems are intended to treat all the water entering the house. Generally, the more time the water remains in contact with the carbon and the greater its surface area, the more contaminants can be removed. Activated carbon filters typically come with a rating indicating the size of the particles they can remove; 0.5 microns is most effective and 50 microns is least effective.

Considerations

• Whole-house activated carbon filters can remove various organic compounds from the water supply, thereby improving taste and color. They can also reduce the level of chlorine, trihalomethanes, industrial solvents, PCBs, pesticides and polycyclic aromatics. The carbon filter, however, will not remove or reduce the concentration of sodium, fluoride, nitrates or calcium and magnesium, nor will they remove microbes. Just like any other filter, the activated carbon must be replaced periodically to remain effective, so it's important to keep track of how long your unit has been installed and how often it should be maintained. Using activated carbon filters to remove sediment is not a good idea because they can become clogged quickly. If you have problems with sediment in your water, consider installing a different kind of filter to trap the sediment and then feeding the water through the whole-house carbon filter to remove other problem contaminants.