In this article we will discuss the details of various types of water filtration systems currently used.

Activated Carbon Filters


Activated Carbon (Image Courtesy: Wikipedia.org)

Activated Carbon (Image Courtesy: Wikipedia.org)


Activated carbon, also called activated charcoal, activated coal or carbo activatus, is a form of carbon that has been processed to make it extremely porous and thus to have a very large surface area available for adsorption or chemical reactions.

Activated carbon filters adsorb organic contaminants that cause taste and odor problems. Depending on their design, some units can remove chlorination byproducts, some cleaning solvents, and pesticides.

To maintain the effectiveness of these units, the carbon canisters must be replaced periodically. Activated carbon filters are efficient in removing metals such as lead and copper if they are designed to absorb or remove lead.

Ion Exchange Filters


Reverse Osmosis Filter

Reverse Osmosis Filter


Because ion exchange units can be used to remove minerals from your water, particularly calcium and magnesium, they are sold for water softening. Some ion exchange softening units remove radium and barium from water. Ion exchange systems that employ activated alumina are used to remove fluoride and arsenate from water. These units must be regenerated periodically with salt.

Reverse Osmosis Filters


Reverse osmosis treatment units generally remove a more diverse list of contaminants than other systems. They can remove nitrates, sodium, other dissolved inorganics, and organic compounds.

Distillation Filters


Distillation units boil water and condense the resulting steam to create distilled water. Depending on their design, some of these units may allow vaporized organic contaminants to condense back into the product water, thus minimizing the removal of organics. You may choose to boil your water to remove microbial contaminants. Keep in mind that boiling reduces the volume of water by about 20 percent, thus concentrating those contaminants not affected by the temperature of boiling water, such as nitrates and Pesticides.

No one unit can remove everything. Have your water tested by a certified laboratory prior to purchasing any device. Do not rely on the tests conducted by salespeople that want to sell you their product.

The below table shows the comparison of various water filtration technologies (Source: EPA)

Water Treatment Methods
Method What It Does to Water Treatment Limitations
Activated Carbon Filters (includes mixed media that remove heavy metals) Adsorbs organic contaminants that cause taste and odor problems. Is efficient in removing metals such as lead and copper.
Some designs remove chlorination byproducts. Does not remove nitrate, bacteria or dissolved minerals.
Some types remove cleaning solvents and pestisides.
Ion Exchange Filters (with activated alumina) Removes minerals, particularly calcium and magnesium that make water “hard.” If water has oxidized iron or iron bacteria, the ion-exchange resin will become coated or clogged and lose its softening ability.
Some designs remove radium and barium.
Removes fluoride.
Reverse Osmosis Filters (with carbon) Removes nitrates, sodium, other dissolved inorganics and organic compounds.
Removes foul tastes, smells or colors.
May also reduce the level of some pesticides, dioxins and chloroform and petrochemicals.
Distillation Filters Removes nitrates, bacteria, sodium, hardness, dissolved solids, most organic compounds, heavy metals, and radionucleides. Does not remove some volatile organic contaminants, certain pesticides and volatile solvents.
Kills bacteria. Bacteria may recolonize on the cooling coils during inactive periods.