Activated Carbon Filters: Everything You Need to Know

Activated Carbon Filters: Everything You Need to Know

Are you considering a carbon filter to treat your home’s water but don’t know much about them? This article can help.

Carbon filters work by trapping harmful chemicals and impurities in the water. They can remove chlorine, lead, mercury, pesticides and herbicides from your drinking water. These filters are a great way to improve the taste of your water as well as its quality!

When selecting a carbon filter, there are several factors you need to consider, including the type of filter, the size of the unit, and how often it will need to be replaced. You also need to think about the type of carbon because this affects which contaminants can be removed and how well the filter treats your water. We explain all of these considerations and more – so keep reading!

In this blog post, we discuss the benefits of activated carbon filters, explain how they work, and share some valuable tips to keep them working properly. We’ll also answer some common questions about these filters, so you can be sure to choose the right one for your home.

What Are Carbon Filters Used For

Granular activated carbon media
Granular activated carbon is the most common size used in residential treatment systems.

Activated carbon filters are used to improve the quality and taste of water. They can remove contaminants such as VOCs, taste and odor compounds, and chlorine. Carbon filters also reduce your environmental impact compared to traditional water treatment methods like reverse osmosis.

What contaminants do carbon filters remove from water

Carbon filters are used to remove many impurities from drinking water. Below is a list of contaminants that can be removed using activated carbon along with a rating of how well carbon removes it.

ContaminantCategoryHow Well Does Carbon Remove This Compound
2-Methyl benzenamineVOCExcellent
Benzoic acidfood preservativeExcellent
Benzyl alcoholalcoholExcellent
Bis(2-chloroethyl) etheretherExcellent
Calcium HypochloritedisinfectantExcellent
Carbon tetrachlorideVOCExcellent
ChloroformDisinfectant ByproductExcellent
cis-1,2- DichloroethyleneVOCExcellent
Desethyl atrazineherbicideExcellent
Diethyl phthalateSVOCExcellent
Diisopropyl atrazineherbicideExcellent
Di-n-butyl phthalateSVOCExcellent
Methyl Isobutyl KetoneVOCExcellent
Methyl naphthaleneSVOCExcellent
o-Phthalic acidVOCExcellent
PFASorganicExcellent to Fair
p-Bromophenolwood preservativeExcellent
Pentachlorophenolwood preservativeExcellent
trans-1,2- DichloroethyleneVOCExcellent
Vinyl acetateVOCExcellent
Acetic acidacidFair
Ethyl acetateVOCFair
Ethyl etheretherFair
Freon 11refrigerantFair
Freon 113refrigerantFair
Freon 12refrigerantFair
Methionineamino acidFair
Methyl ethyl ketoneVOCFair
Methyl-tert-butyl etheretherFair
Table of contaminants removed by activated carbon with an assessment of how well carbon removes each compound.

How Do Carbon Filters Work

Carbon filters work by trapping harmful chemicals and impurities in the water. Activated carbon is porous, which means it has a large surface area that can adsorb pollutants. The activated carbon filter traps these pollutants in the pores of the media, where they are removed from the water.

Adsorption process

Carbon filters trap contaminants through a process called adsorption. Adsorption is a physical process where molecules attach to the outside surface of a solid. It is not the same as absorption, where liquids are soaked into a sponge. In adsorption, the contaminants stick to the surface of activated carbon rather than being absorbed into it.

Carbon is activated to create thousands of pores. Pores, which are tiny holes in the carbon, are key to its ability to adsorb contaminants. The more porous the activated carbon, the better, as this will increase the amount of surface space available for contaminants to latch onto when air passes through the filter. Surface area is the key to carbon’s adsorption capacity.

The activated carbon attracts and binds with certain chemicals and impurities in water while allowing water and dissolved ions to pass through.

What is carbon made from

Carbon is made from organic materials such as coal, wood, coconut shells, or peat. Most carbon is made from coal. Carbon made from coconut shells has many desirable properties. It is very effective at removing many of the toxic chemicals found in drinking water. It also removes chlorine and taste compounds to make water pleasant to drink.

The raw material is burned in the absence of oxygen to create charcoal. This process is known as pyrolysis. The charcoal is pure carbon – all of the water, hydrogen, and impurities are driven off.

Charcoal is converted into activated carbon by exposing it to steam. The steam creates thousands of tiny pores that increase the surface area of the carbon. This makes it more effective at adsorbing contaminants from water.

How is carbon activated

Carbon is activated to create thousands of pores. Pores, which are tiny holes in the carbon, are key to its ability to adsorb contaminants. The more porous the activated carbon, the better, as this will increase the amount of surface space available for contaminants to latch onto. Surface area is the key to carbon’s adsorption

Benefits of Carbon Filters

Carbon filters offer many benefits for people looking to have clean, pure drinking water.

  • Carbon filters are less expensive to operate and maintain than reverse osmosis systems.
  • They do not require electricity, which makes them ideal for use in remote areas or developing countries.
  • Activated carbon is environmentally friendly and can be recycled.
  • Carbon filters are effective at removing a wide range of contaminants, including chlorine, benzene, pesticides, and herbicides.
  • They also remove unpleasant taste and odor compounds from water to make it more palatable.
  • Charcoal filters are well understood – they have been used for centuries to purify water.
  • Carbon filters are simple to install and maintain.

Important Factors When Selecting a Carbon Filter

Carbon filters are an affordable and effective way to remove many of the contaminants from drinking water. When selecting a carbon filter to treat your home’s drinking water, there are a few important factors to consider.

Amount of carbon

Activated carbon filters for POU systems
The amount of carbon in a filter affects how long it will last and the mass of contaminants it can remove from your drinking water.

The amount of carbon in a filter is important. The more carbon the filter has, the longer it will last before you have to replace it. This saves time and, in the long run, is less expensive compared to small filters. Look for a filter that has a more activated carbon.

Read my carbon design guide for more information on this subject.

Type of carbon

The type of carbon is also important. Some carbons are better at removing certain contaminants than others. You need to choose a carbon that is specifically designed to remove the contaminants in your water supply.

Coconut shell is ideal for treating drinking water. It can remove many of the contaminants you’re likely to find in your water. It also removes taste and chlorine. Learn more about coconut shell carbon in my article.

Water flow is important

The size of the filter will determine how quickly water can pass through it. You don’t want a filter that can only provide a trickle flow rate because you’ll be waiting a long time for your water to be filtered. Choose a filter that can handle the maximum flow rate of your faucet or water source.

Change carbon filter

The amount of activated carbon in your filter has a certain amount of treatment capacity. Once the carbon is spent, it can no longer remove contaminants from your water. You will need to replace the filter with a new one.

Check the manufacturer’s recommendations for how often to change the filter. It’s usually every six months to a year, depending on the amount of water you use and the type of carbon in the filter.

If your water is especially contaminated, you should change the filter more frequently. Also, if you use a lot of water for things like watering plants or filling a pool, you’ll need to change the filter more often.

It’s important to know that not changing your carbon filter regularly could lead to contaminated water. Filters also collect dirt and debris and can become clogged. This can cause reduced pressure and flow in your system. Over time, bacteria can collect in carbon filters which can make you and your family sick.

NSF certification

NSF International is an independent, third-party testing organization that certifies water treatment equipment. They verify the claims manufacturers make for their products.

Look for NSF certification on the carbon filter you select to ensure it has been tested and certified to meet strict standards for contaminant removal. NSF certifies carbon filters for the following benefits:

  • Contaminant reduction claims for Aesthetic Effects
  • Contaminant reduction claims for Health Effects
  • Contaminant reduction claims for Emerging Compounds/Incidental Contaminants
  • Shower Filtration Systems

Types of Carbon Filters

Carbon filters come in a variety of sizes and configurations. You can find a filter that treats every drop of water that comes into your house or one that just treats the water in your fridge. It’s important to know what types of carbon filters are available and what their benefits and limitations are.

Here is a summary of the carbon filters you can use in your home.

Whole-house systemWhole house carbon filter

A whole-house carbon filter system is installed on the main water line entering your house. This filter will treat all the water that comes into the house–from the faucets in the kitchen and bathroom to the washing machine and dishwasher. This type of filter is also known as a point-of-entry (POE) system.

The whole-house system is a good choice if you want to make sure all of your water is filtered and treated for contaminants. This is a good solution if the contaminant you’re removing is unsafe to drink or can volatize and become a breathing hazard. This way, you’ll have clean water at your kitchen sink for drinking as well as your bathroom for brushing your teeth and bathing.

Advantages of POE carbon filters are they have a long service life so you don’t have to replace the spent carbon more than once or twice a year. Some filters have a 2-year bed life. They are usually much easier to service because they are installed in an open area in your basement or service room.

A disadvantage of whole-house filter is that it can be expensive to install and may require the services of a plumber. The filter will also need regular replacement, depending on the amount of water you use.

Check Pricing

Under-sink carbon filterUnder sink carbon filter

Sometimes you only need to filter the water that you drink and cook with. In this case, you can use an under-sink carbon filter. This type of filter is installed under your sink and filters the water before it enters your faucet. This type of filter is also known as a point-of-use (POU) filter.

The advantage of using an under-sink carbon filter is that it’s convenient and takes up very little space. You can often install these filters yourself if you’re a DIYer.

The disadvantage is that these filters usually have a small treatment capacity. So, if you have a large family or use a lot of water, this may not be your best option.

Faucet filter

If you want to remove impurities for drinking water or brushing your teeth, you can use a faucet-mounted carbon filter. These filters screw onto the end of your kitchen or bathroom faucet and are easy to install.

The advantage of using a faucet-mounted filter is that it’s convenient – you always have clean water when you need it. Plus, you can usually install this type of filter yourself without special tools. The initial purchase cost for this type of filter is relatively low.

The disadvantage is that these filters usually have a small treatment capacity. So, if you have a large family or use a lot of water, this may not be your best option. In addition, the cost for replacement filters is relatively high, so this method may not be the most cost-effective in the long run.

Shower filter

If you’re concerned about the impurities in your shower water, you can use a shower filter. These filters attach to your shower head and remove chlorine, heavy metals, and other contaminants from your water.

The advantage of using a shower filter is that it can help reduce the amount of chlorine in your water. This can be especially helpful if you have dry skin or hair.

The disadvantage is that shower filters usually don’t remove as many contaminants as whole-house or under-sink filters. So, if you’re looking for a comprehensive filtration solution, this may not be the

Refrigerator filter

If you’re only concerned about filtering the water that goes into your fridge, you can use a refrigerator carbon filter. This type of filter is installed in your fridge’s water supply and filters out chlorine, lead, and other contaminants.

The advantage of using a refrigerator carbon filter is that it’s easy to install – you just connect it to your fridge’s water supply.

The disadvantage is that many of these filters have a limited treatment capacity. If you have a large family or need a lot of water, this may not be the best option for you. Replacement filters, on the other hand, are not inexpensive and the costs add up quickly over time.

Read my article on refrigerator water filters and chlorine treatment.

Pitcher filter

Many people use pitcher filters to filter their drinking water. Brita is the most well-known type of pitcher filter. These filters have special carbon filter cartridges that are inserted into the pitcher. The water is treated as you pour the water into the pitcher.

The advantage of using a pitcher filter is that it’s easy to use and doesn’t require any installation. You can also take the pitcher with you on trips, so you always have clean water available.

The disadvantage is that pitcher filters don’t remove as many contaminants as some other types of filters.

Which Type of Carbon Filter Do I Need

Give the various types of carbon filters available, how do you know which type of carbon filter is best for your needs?

The first step is to figure out what kind of contaminants you want to remove from your water. If you’re only concerned about removing chlorine, a faucet-mounted or shower filter may be the best option for you. If you’re looking to remove a contaminant that is unsafe to drink, you may need a whole-house or under-sink filter. For volatile compounds that can create breathing hazards, you definitely want a whole-house system to protect your family.

ContaminantRisk or HazardBest Type of Filter
Taste or odor compoundAestheticPoint-of-use
Disinfectant byproductsHealth risk by drinkingPoint-of-use
LeadHealth risk by drinkingPoint-of-use or



PFASHealth risk by drinkingPoint-of-use or



GasolineHealth risk by drinking or breathingPoint-of-entry
SolventHealth risk by drinking or breathingPoint-of-entry


What does activated carbon not remove from water?

Activated carbon filters can remove chlorine, bad tastes and odors, and some VOCs. However, they cannot remove fluoride, arsenic, or nitrates from the water. Additionally, activated carbon filters may not be effective at removing some pesticides and pharmaceuticals from the water.

How long will my carbon filter last?

Activated carbon filters typically have a lifespan of around six months to one year, depending on the quality of the filter and how often it is used. However, some filters may last longer or shorter than this timeframe.

Are charcoal filters the same as activated carbon filters?

Charcoal filters are a type of carbon filter. However, charcoal has not been activated. This is the process in which steam is used to make thousands of pores in the carbon, which allows it to adsorb more contaminants. Activated carbon filters are more effective than charcoal filters at removing contaminants from water.

Can I use an activated carbon filter on my fish tank?

Yes, you can use an activated carbon filter on your fish tank. However, it is important to note that not all activated carbon filters are

What size filter do I need?

The size of the filter you need depends on the gallons per day (GPD) rating of your water system. Most homeowners’ systems require a filter with a GPD rating of

What is coconut shell carbon?

Coconut shell carbon is a type of activated carbon that is made from the shells of coconuts. It is considered to be a higher quality activated carbon than other types, such as coal-based activated carbon. Coconut shell carbon can remove more contaminants from water and has a longer lifespan than other types of activated carbon.

Final Take

Carbon filters are a great way to remove impurities from water. In order to get the most out of your carbon filter, it’s important that you select one with the right amount of surface area and pore size for the volume of water you need filtered. This will be based on how much water is typically consumed in a day by individuals living in your household or office space. Additionally, some people prefer certain types of filters over others because of cost, ease of installation, or maintenance requirements.

We hope this blog post has helped you understand what carbon filters are and how they work.

Boch Richard

Richard Boch is a chemical engineer responsible for designing water filtration systems for industrial and residential customers. He has more than 20 years of experience with ion exchange, activated carbon, and reverse osmosis. Richard's expertise has made him a go-to source for municipalities and businesses looking to improve their water quality. When he's not working, Richard enjoys spending time with his wife and two young children.

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