Due to the growing awareness of water contamination over the last few decades, the consumer market has seen a wide array of water filter products using a variety of different water filtration technologies. To help you better understand the differences between these technologies, we have compiled this brief overview of water filtration technologies, noting their relative advantages and issues.

Granular Activated Carbon

Loose granular activated carbon.

Very commonly used in consumer filtration products, from filtered water pitchers to aquarium filters to air purifiers.

Overview:

Granular Activated Carbon (GAC) utilizes a bed of carbon granules to passively filter water as it passes through. Larger particulate matter can be trapped by the GAC, and certain contaminates that affect the taste and odor of water are physiochemically adsorbed to the carbon granules. It is one of the most common and basic of water filtration technologies.

Benefits:

  • Utilizes mechanical filtration and physiochemical adsorption to improve the taste and odor of water.
  • No active water pressure required; can be used for passive filtration.
  • No wasted water.
  • No electricity required.
  • No healthful minerals removed from the water.

Issues:

  • Not effective in treating contaminants of health concern.
  • Prone to water channeling effect; water can form a channel through the GAC to bypass the filter media entirely.
  • Prone to bacterial growth without the use of chemical additives.

Distillation

Distillation equipment.

Used in distiller home appliances and as an end product (distilled water) sold in supermarkets.

Overview:

Through Distillation, water is boiled to a vapor and then cooled back to a liquid, separating out inorganic contaminants in the process. While useful in the reduction of heavy metals, distillation is not effective in the reduction of volatile organic compounds (VOCs), which can be evaporated into a gas and condensed back into a liquid along with the water. The slowly processing water distillers generally use a separate container for filtered water storage, which means that compared to some other water filtration technologies, it cannot treat water immediately for consumption.

Benefits:

  • Can reduce the presence of heavy metals in the water.
  • No physical filter media required.

Issues:

  • Not effective in treating VOCs in the water.
  • Requires high levels of electricity for operation.
  • Distillation is a relatively slow process.
  • Available drinking water limited to the amount stored after distillation.
  • Distillation process removes healthful minerals from the water.

Ceramic Filters

Ceramic filter cartridges.

Used in certain consumer water filtration systems.

Overview:

Ceramic Filters use mechanical filtration to prevent certain contaminants from passing through the pores of the filter surface. Contaminants larger than the pore size, including large bacteria, protozoa, or cysts, are prevented from passing through the filter with the water. It is also somewhat common among water filtration technologies.

Benefits:

  • Utilizes mechanical filtration to improve the taste, odor, and healthfulness of the water.
  • Solid filter media means that no water channeling effect occurs.
  • Can be used for passive water filtration.

Issues:

  • Ceramic filter media is prone to hairline cracks or breakage.
  • Does not use physiochemical or electrokinetic adsorption to reduce contaminants smaller than the pore size.
  • Does not prevent the growth of mold or algae on the filter without chemical additives.

Reverse Osmosis

Reverse osmosis system.

Used in consumer Reverse Osmosis point-of-use drinking water systems.

Overview:

Reverse Osmosis (RO) involves the application of pressure to force water through a semi-permeable membrane, allowing water to pass through the membrane while contaminants such as heavy metals, salts, and inorganic compounds remain behind. A typical RO system utilizes one or more sediment prefilters to trap particulate matter in the water, as well as a solid carbon block prefilter to trap organic chemicals and chlorine before the water reaches the RO membrane. In addition, an optional solid carbon block post-filter is used to trap contaminants not removed by the RO membrane, as well as an optional ultraviolet (UV) lap to sterilize any remaining microbes in the water. Processed water is held in a reservoir tank for use.

Benefits:

  • Multiple methods of filtration can be involved: mechanical filtration, electrokinetic adsorption, physiochemical adsorption, reverse osmosis, and ultraviolet sterilization.
  • Utilizes the strengths of multiple types of water filtration technologies.
  • No water channeling effect

Issues:

  • Requires active water pressure for use. Passive filtration is not possible.
  • Wastes 3 to 4 gallons of water for each gallon of drinking water produced.
  • Available drinking water limited by reservoir tank; once empty, the RO system requires one or more hours to refill the tank.
  • Requires electricity for optional UV sterilization.
  • Requires multiple filter cartridges.
  • RO process removes healthful minerals from the water.

Ultraviolet Treatment

Industrial ultraviolet purification light.

Often used as an anti-microbial supplement to existing drinking water treatment devices.

Overview:

With Ultraviolet (UV) Treatment, water passes through a chamber where it is exposed to UV radiation. The UV radiation is effective at treating certain bacteria and cysts in the water, but is otherwise limited in scope compared to other water filtration technologies.

Benefits:

  • Reduces the presence of certain harmful bacteria and cysts in the water.
  • No wasted water.
  • No chemicals added to the water.
  • Does not remove healthful minerals from the water.

Issues:

  • Does not treat contaminants outside of certain bacteria and cysts, such as heavy metals, viruses, and VOCs.
  • Effectiveness is reduced as water turbidity increases (i.e., effectiveness is reduced when the water is cloudy or full of particulates).
  • Requires electricity for operation.

Multipure’s Solid Carbon Block

Multipure filter cartridges

Multipure carbon block filters.

Used in Multipure Drinking Water Systems; generic carbon blocks are used in a variety of other drinking water systems on the market.

Overview:

Blending industry-leading filtration performance, cost-effectiveness, efficiency, and convenience, Multipure’s Solid Carbon Block Filter uses a combination of mechanical filtration, electrokinetic adsorption, and physiochemical adsorption, making it a product of choice among water filtration technologies. The solid carbon block prefilter electrokinetically adsorbs contaminants before the water passes into the main carbon block, where the densely compacted carbon block’s microscopically-small pores mechanically intercept particles as small as 0.5 microns. Remaining contaminants are physiochemically adsorbed to the carbon block as water passes through. The large surface area of the carbons provides maximum contact with the water for maximum filtration.

Benefits:

  • Utilizes three types of filtration: mechanical filtration, electrokinetic adsorption, and physiochemical adsorption
  • Very high filtration surface contact area
  • No water channeling effect
  • No wasted water
  • No electricity required
  • No chemicals added to the water
  • No healthful minerals removed from the water

Issues:

  • Does not treat bacteria or viruses.
  • Requires active water pressure for operation.

Multipure’s PureBlock

Multipure Aqualuxe drinking water purifier.

Proprietary carbon-block-based water filter used only in Multipure’s Aqualuxe Drinking Water Purifier.

Overview:

Multipure’s proprietary PureBlock technology offers bacteria, virus, and cyst removal from drinking water without the need for chemical additives or external power requirements. PureBlock builds upon Multipure’s superior carbon block filter technology to purify water by up to 6-factor reduction (99.9999%) of bacteria and 4-factor reduction (99.99%) of viruses and cysts. PureBlock conveys all the advantages of Multipure’s carbon block water filtration technologies with the added benefit of exceptional microbiological purification.

Benefits:

Issues:

  • Requires active water pressure for operation.