Types of House water filters:

  1. Point of Entry
  2. Point of Use

Both types of filters use one or a combination of different water filter technologies.

The Basics of Common Water Filter Technologies

  • Activated Carbon
  • Charcoal Filters
  • Ceramic
  • Ion Exchange Resins
  • Distillation
  • Mechanical Filtration
  • Reverse Osmosis
  • Ultra-Violet Sterilization
  • Ozone

Activated Carbon: Carbon filters usually come in two types, granulated activated carbon and carbon block, although they vary significantly when it comes to effectiveness. Some of them simply improve the taste and odor of water through the removal of chlorine, while other filters eliminate a broad range of contaminants, such as mercury, lead, asbestos, and volatile organic compounds (VOCs). Activated carbon bonds with some contaminants chemically and removes them however, it is ineffective against common inorganic pollutants like nitrate, arsenic, perchlorate, fluoride, and hexavalent chromium.

Charcoal Filters: Also known as carbon block filters, these hold pulverized activated carbon. Using high pressure, the carbon is shaped into blocks. These filters are usually more effective because of their larger surface area when compared to granulated activated carbon filters, granted they have a sufficiently quick flow of water.

Ceramic: Solid contaminants including sediments and cysts are blocked by the small holes punched across the surface of the material but chemical contaminants are not removed.

Ion Exchange Resins: An ion exchange process is used in these filters to eliminate mineral salts and ions (other electrically charged molecules) from the water. This process does not remove non-ionic contaminants such as trihalomethanes, microorganisms, and other common volatile organic compounds. It is usually used for water softening, where calcium and magnesium are replaced with sodium.

Distillation: This process removes various kinds of bacteria, chemicals, viruses and minerals with a boiling point higher than that of water by first heating the water to vaporize it, and then condensing the resultant steam back into water. Distillation cannot however, remove trihalomethanes, chlorine or volatile organic chemicals (VOCs).

Mechanical Filters: Riddled through with tiny holes, like their ceramic counterparts, these filters are used for the removal of contaminants that include sediments and cysts. Mechanical filters are ineffective against chemical contaminants are used both alone and in a combination with other filtering technologies.

Reverse Osmosis: Water is pushed through a semi-permeable membrane in this process. The membrane blocks any particles that are larger than the water molecules. Reverse osmosis can be used for the removal of several contaminants that are not eliminated by activated carbon, such as nitrates, arsenic, perchlorate, fluoride, and hexavalent chromium. This process will not however, remove trihalomethanes, chlorine, or volatile organic chemicals (VOCs). Therefore, numerous reverse osmosis systems are combined with an activated carbon component so that all contaminants are effectively removed. Consumers should be mindful of the fact that these filters use up anywhere from 3 to 20 times the amount of water they produce and that there are significant variations in quality for both the carbon filters and the membrane systems. Considering the waste of water, reverse osmosis systems are ideal only for cooking and drinking water purposes.

Ultra-Violet (UV) Sterilization: Most microorganisms and bacteria are eliminated from the water using ultraviolet light. These systems cannot however, remove chemical contaminants.

Ozone: Ozone is usually used in a combination with another filtering technology and while it is not particularly effective at chemical contaminant removal, it does successfully eradicate bacteria and any other microorganisms present in the water.