Carbon Water Filter: What is it and how does it work?

Chlorine is a common contaminant found in home water because city municipalities use chlorine and chloramine chemicals to treat water. It’s common to have chlorine leftover that affects the smell and taste of your water. Using a carbon water filter helps remove the chlorine taste and odor in the tap water so you have pure and refreshing water.

What is a Carbon Water Filter?

A carbon water filter is a water filtration media that removes chlorine, bad taste, and odors from tap water. Carbon filters also remove some heavy metals and chemicals. Water treatment systems such as reverse osmosis, water filter pitchers, whole house water filters, faucets, shower filters, refrigerator filters, backpacking filters, and more utilize carbon water filters.

Carbon filters are made from organic raw materials that are high in carbon. Such raw materials include coal, wood-based, or coconut shell. In water filtration, we don’t use coal because of the arsenic that comes from mining. We use coconut shell to make carbon filters because it is renewable and good for filtration.

The raw material is heated in the absence of oxygen to increase the surface area of carbon.  Also, heating the filter gives carbon more capacity to hold contaminants. That’s why it’s also known as a charcoal filter.

A carbon filter has a large surface area, therefore, has more capacity to hold impurities.

How does the carbon water filter work

A carbon water filter removes contaminants using the adsorption method. The filter soaks/absorbs contaminant particles in water like a sponge. The particles stick in the filter, and clean water passes through.

Note how the sponge absorbs (with B) but carbon adsorbs (with d). The sponge absorbs water, which means when you squeeze it using your hand it releases water, but carbon soaks contaminants when you squeeze it. It does not release water, so contaminants remain in it.

What to check when buying a carbon filter

  • Pore size

The filter pore size is measured in microns. If the micron is small, the better, because the finer the filtration. The range is from 0.5 up to 50 microns.

  • Flow rate

The lower the flow rate or low water pressure, the more time for water contact with the surface of the filter and the more contaminants the filter soaks.

The more contact time the water has with the carbon filter surface, the more efficient filtration means the filter will soak up more contaminants.

  • Types of carbon filter

The carbon water filter is available in two types: backwashing filter and cartridge filter style.

The cartridge filter style includes a granular activated carbon filter (GAC), an activated carbon block (ACB), a catalytic carbon filter, and a coated carbon filter.

  1. Granular Activated Carbon filter (GAC)

The Granular Activated Carbon filter focuses on capturing chemical contaminants such as chlorine, radon, and VOCs (volatile organic compounds).

It also removes cloudiness, offensive odors, colors, and unpleasant tastes.

After using the GAC filter for a specific period, the ability to remove the chemical is used up and requires changing to work effectively.

The GAC water filter is used mostly for polishing but can be used as a pre-filter.

  1. Activated carbon block (ACB)

The Activated Carbon Block filter removes chlorine and VOCs (volatile organic compounds), including insecticides and pesticides.

It also removes chemicals causing bad taste and odors.

The Activated Carbon Block filter focuses on the taste and drinkability of your water while removing chemicals.

  1. Catalytic carbon water filter

A catalytic carbon water filter is a carbon block that has a special coating that enhances the adsorption process, making it good for removing chloramine. Nowadays, municipalities have started to use chloramine to treat water. Chloramine is a chlorine and ammonia compound. It takes a lot of time for activated and granular activated carbon to remove chloramine, so catalytic carbon water filters help remove chloramine.

  1. Coated carbon water filter

A coated carbon water filter is a carbon block that has a special coating/blend that helps remove sediment, arsenic, dissolved inorganic compounds, and lead.

We know carbon water filters are good for removing volatile organic compounds such as chlorine and chemicals (herbicides and pesticides).

If you want to remove sediment, arsenic, dissolved inorganic compounds, and lead using a carbon filter, you must blend or coat it with something else. Some companies call it an impregnated carbon filter.

  1. Backwashing carbon filter

The backwashing carbon filter uses a tank to store filtering media. Contaminated water passes through the media inside the tank that removes it.

After treating water for some time, the system automatically cleans itself through a process called backwashing.

During the backwashing process, the contaminants the media has collected flush away, leaving you with clean media to treat water.

Best backwashing carbon filter

Oceanic Whole House Carbon Water Filtration Backwash System

Oceanic Whole House Carbon Water Filtration Backwash System

Carbon tank Filter system

Carbon tank Filter system

Watch the video to understand the difference between a carbon backwash filter and a cartridge.

What contaminants does the carbon filter remove?

Carbon takes care of contaminants that are organic in nature, such as

  • Volatile organic compounds
  • Chlorine, taste, and odor
  • Perfluorooctanesulfonic acid (PFOS) is used to make fabric, carpet, and paper packaging for food and furniture.
  • Pharmaceuticals: a chemical found in drugs that can get into water through improper disposal of drugs.
  • Pesticides and herbicides

Carbon is not good at removing arsenic, dissolved inorganic compounds, and lead. It requires special material blended with carbon to remove lead.

How often are you supposed to change the carbon filter?

Changing the carbon filter depends on the contaminant’s level and water use. If contaminants level and water usage are low the filter can last for long but if the case is vice versa you require frequent change.

It is recommended to replace the carbon filter every six months or one year. If you wait too long, the filter pores will become full, causing the collected particles to break from the carbon and eventually flow into your water supply.

Where to install a carbon filter

A carbon water filter can be installed at the point of entry and point of use.

A point of entry is installed to treat water for the whole house. They are installed at the main water supply and treat all water entering your whole house.

The Point of use is installed before you drink, use for cooking, or bathing.

The Best Carbon Water Filter for Your Home

The best carbon water filter for your home is a Granular Activated Carbon filter (GAC) and Activated carbon block (ACB).

The best Activated carbon block (ACB) include

NameImageWhere to buy
1Express WaterExpress Water Activated Carbon Block Replacement water FilterAmazon
2EcoPure EPW4C Carbon Block EcoPure EPW4C Carbon Block Whole Home Replacement Water FilterAmazon
3iSpring FC15B CTO Carbon BlockiSpring FC15B Whole Filter CarbonAmazon
4APEC Water Systems activated carbon FILTERAPEC Water Systems 20Amazon
5Pentek pentair big blue carbon cartridgePentair Pentek EPM-20BB Big Blue Carbon Water FilterAmazon
6Ronaqua Block Activated Carbon Coconut Shell Water Filter CartridgeRonaqua Block Activated Carbon Coconut Shell Water Filter CartridgeAmazon
7Whirlpool WHA2BF5 Activated carbon block Water FilterWhirlpool WHA2BF5 carbon block Water Filter Amazon
8DuPont WFPFC8002 Universal Whole House DuPont WFPFC9001 Universal Carbon Block Whole House Water Filter CartridgeAmazon
9SimPure Carbon Water FilterSimPure 5 Micron 10 Amazon
10Aquaboon Coconut Shell Water Filter CartridgeAquaboon Coconut Shell Water Filter Cartridge Activated Carbon Block Amazon
11PUREPLUS CTO Carbon Water Filter CartridgePure plus Carbon Water Filter Cartridge ReplacementAmazon
12Filtrete Carbon Wrap Water Filter 3WH-STDCW-F02Filtrete Standard Capacity Whole House Replacement Carbon Wrap Water Filter Amazon
13Tier1 EP-20BB Carbon BlockTier1 5 Whole House Activated Carbon Block Water Filter Replacement Cartridge Amazon
14GOLDEN ICE PURE Whole House CTO Carbon
15Ice pure Whole House Water FilterICEPUREActivated carbon Whole House Water Filter

Shop for the best Granular Activated Carbon filter (GAC)

  1. Pentek – 155247-43 RFC-20BB Carbon Filter (20″ x 4.5″), 25 Micron (big blue)
Pentair Pentek RFC-20BB Big Blue Carbon Water Filter
  1. Express Water Granular Activated Carbon Replacement Filter
Express Water Granular Activated Carbon Replacement Filter


  • Size: 4.5” x 20”
  • Filtration Size: 5 Microns
  • Max PSI: 80psi
  • Max Temperature: 100°F (38°C)
  • Material: Polypropylene Shell and Coconut Husk Carbon
  • Life Cycle: 6 months or earlier depending on the quality of your incoming water

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