Activated Carbon Filters: How They Work and Why You Need One

Activated Carbon Filters: How They Work and Why You Need One

Discover the Science Behind Activated Carbon Filters for Cleaner Water.

Table of Contents

  1. Introduction
  2. Understanding Activated Carbon Filters
    • What are Activated Carbon Filters?
    • The Science Behind Activated Carbon Water Filters
    • How Do Activated Carbon Filters Work?
  3. Benefits of Using Activated Carbon Filters
    • Key Benefits
  4. Types of Activated Carbon Filters
  5. Applications of Activated Carbon Filters
  6. What Carbon Filters Remove
  7. Choosing the Right Activated Carbon Filter
  8. Installation and Maintenance
    • Installation
    • Maintenance
  9. Are Carbon Water Filters Safe?
  10. Frequently Asked Questions (FAQs)
  11. Alternatives to Carbon Water Filters
  12. Conclusion


Activated carbon filters are essential for ensuring the water in your home is clean, safe, and free from harmful contaminants. These filters are widely used in various applications, from whole-house water treatment systems to individual drinking water filters. Understanding how they work and why you need one can significantly impact your health and the environment.

Understanding Activated Carbon Filters

What are Activated Carbon Filters?

Activated carbon filters, also known as activated charcoal filters, are made from carbon processed to have an extensive surface area with tiny, low-volume pores. These pores are crucial for the adsorption process, where contaminants are trapped on the surface of the carbon material.

The Science Behind Activated Carbon Water Filters

What Is Activated Carbon?

Activated carbon is carbon processed to increase its surface area significantly. One gram of activated carbon has over 32,000 square feet of surface area, which enhances its ability to adsorb contaminants.

  • Source Materials: Activated carbon can be derived from various materials, including wood, bamboo, sawdust, coconut shells, peach pits, petroleum pitch, and coal.

  • Activation Methods:
    • Thermal Activation: Involves using hot gases and steam in an inert atmosphere to create a highly porous structure.
    • Chemical Activation: Chemicals are added before carbonization, followed by heating to create the porous structure.

How Do Activated Carbon Filters Work?

Activated carbon filters work primarily through adsorption, a process where contaminants are trapped on the surface of the carbon. This process is enhanced by the large surface area and porous nature of the activated carbon.

  • Physical Adsorption: Intermolecular forces draw molecules into the pores of the activated carbon.
  • Chemical Reactions: For example, chlorine reacts with carbon to form chloride ions, effectively removing chlorine from the water.

Benefits of Using Activated Carbon Filters

Key Benefits

Activated carbon filters offer numerous benefits, making them a popular choice for home water treatment.

  • Removal of Contaminants: Effective at removing chlorine, chloramine, volatile organic compounds (VOCs), and other harmful substances.
  • Health Benefits: Improves the taste and quality of drinking water, and provides benefits for skin and hair by removing harmful chemicals.
  • Environmental Benefits: Reduces the need for bottled water, thereby decreasing plastic waste and promoting eco-friendly practices.

Types of Activated Carbon Filters

Different Types of Activated Carbon Filters

  1. Granular Activated Carbon (GAC) Filters
    • Loose particles that allow easy water flow but can lead to channeling.
  2. Carbon Block Filters
    • Fine granules held together with a bonding agent, providing more surface area and preventing channeling.
  3. Powdered Activated Carbon (PAC) Filters
    • Fine particles used in carbon block filters.
  4. Extruded Activated Carbon (EAC)
    • Cylindrical or spherical particles used in gas phase applications.
  5. Impregnated Carbon
    • Contains inorganic compounds like silver, used in water purification.
  6. Bead Activated Carbon (BAC)
    • Spherical particles used in water treatment.
  7. Woven Carbon
    • Woven into fibers for applications like odor absorption.
  8. Polymer Activated Carbon
    • Coated with a polymer for medical use.

Applications of Activated Carbon Filters

Common Applications in Households
  1. Drinking Water Filters
    • Includes pitcher filters, faucet-mounted filters, and under-sink filters.
  2. Whole House Filtration Systems
    • Benefits include treating all incoming water, typical installation and maintenance procedures.
  3. Shower Filters
    • Benefits for skin and hair, easy installation, and maintenance.

Other Uses of Activated Carbon
  • Medical Applications: Treats overdoses, poisoning, indigestion, and diarrhea.
  • Industrial Applications: Purifies metals and removes impurities.
  • Environmental Applications: Groundwater remediation and spill cleanup.
  • Cosmetic Applications: Shampoos, toothpaste, and face masks.
  • Water Purification: Removes a wide range of impurities from water.
  • Air and Gas Purification: Filters out odors, pollutants, and VOCs.
  • Mercury Removal: Traps mercury gas in industrial applications.
  • Gas Storage: Stores fuel gases efficiently.
  • Space Technology: Filters contaminants in spacesuit life support systems.

What Carbon Filters Remove

Impurities Removed by Carbon Filters
  • Common Contaminants: Chlorine, bad tastes, foul odors, trihalomethanes, mercury, pesticides, herbicides, and certain heavy metals.
  • Metals and Microbiological Contaminants: Carbon block filters remove more pollutants, including metals like lead and pathogens.

Activated Carbon and Chlorine
  • Chlorine Removal: Catalytic carbon chemically alters chlorine into chloride, effectively removing it from water.
  • Chloramines: More difficult to remove, but catalytic carbon breaks down chloramine into chloride.

Choosing the Right Activated Carbon Filter

How to Choose the Best Activated Carbon Filter for Your Needs

Factors to Consider

  • Water Quality and Specific Contaminants
  • Filter Lifespan and Replacement Frequency
  • Flow Rate and Filter Capacity

Popular Brands and Models

Brand Model Type Key Features
Renwater MWH-3 Whole House Filter Lead protection, salt-free scale conditioner
Renwater MWH-2 Whole House Filter Sediment protection, salt-free scale conditioner
Renwater MWH-1 Whole House Filter Activated carbon, compact design

Installation and Maintenance


  • Whole-House Filters (Point of Entry)
    • Installed on the home's main water supply.
    • Includes sample ports for water testing and a bypass switch for maintenance.
  • Point-of-Use Filters
    • Installed at specific water outlets, treating water just before it reaches the faucet or appliance.


  • Regular Maintenance
    • Essential to replace filters periodically to maintain effectiveness and prevent bacterial build-up.
    • Filter Replacement Frequency: Generally every six months to one year, depending on water quality and usage.

Are Carbon Water Filters Safe?

Safety of Carbon Water Filters
  • Safety Certifications: Look for third-party ratings like NSF certification for material safety and effectiveness.
  • Multipure's Innovation: Developed the first carbon block filter, effectively treating heavy metals and toxic chemicals without removing beneficial minerals.

Frequently Asked Questions (FAQs)

Frequently Asked Questions About Activated Carbon Filters

  • How long do activated carbon filters last?
    • Typically, they last between six months to one year.
  • Can activated carbon filters remove all contaminants?
    • They are effective for many contaminants but may not remove all, such as fluoride or total dissolved solids (TDS).
  • Are activated carbon filters safe for drinking water?
    • Yes, especially those with NSF certification.
  • What is the difference between activated carbon and charcoal filters?
    • Activated carbon filters have a higher surface area and are more effective than standard charcoal filters.
  • Can activated carbon filters remove fluoride from water?
    • Generally, no, unless combined with other filtration methods like reverse osmosis.

Alternatives to Carbon Water Filters

Alternatives to Carbon Water Filters
  1. Sediment Filters
    • Catch dirt and debris, often used as a pre-filter.
  2. Ceramic Filters
    • Block some living organisms, often combined with carbon filters.
  3. Reverse Osmosis (RO) Systems
    • Use carbon filters to protect membranes and remove additional contaminants.


Why You Need an Activated Carbon Filter

Activated carbon filters are a crucial part of any home water treatment system, offering a wide range of benefits from removing harmful contaminants to improving the taste and quality of your water. With the right filter, you can ensure your family's health and well-being while also contributing to environmental sustainability.