Activated Carbon Filters: What Do They Remove from Water?

Updated: May 20th, 2024

If you’re concerned about the quality of your drinking water, now’s the time to begin exploring different water treatment options to prevent the unthinkable. During your search, you’re likely to encounter a powerful water filer system of water filtration method that has risen in popularity with American households and municipalities: activated carbon filtration.

Generally, water filters can be very effective at diminishing a broad range of contaminants, unpleasant odors, and bad tastes from drinking water. But filters that use activated carbon seem to have some miraculous abilities that ordinary filters lack. Nevertheless, if you want a water filtering system that targets and removes specific contaminants and impurities in drinking water, you must know exactly what contaminants it eliminates and reduces, and those it doesn’t remove.

Activated carbon filters are among the front-runners in the water filtration arena today. Perhaps that stems from their unique properties and ability to effectively remove up to 99% of total suspended solids (TSS), volatile organic compounds (VOCs), sediment, heavy metals, chlorine, chloramines, and a bunch of other contaminants that linger in drinking water.

As such, today, we’re zeroing in on activated carbon filters. We’ll be looking specifically at various aspects, including:

  • How activated carbon filter systems treat water
  • The different types of activated carbon filters
  • What contaminants activated carbon filters remove from water
  • How to determine what kind of carbon filter system to use

Let’s get right to it!

What are activated carbon filters?

Interestingly, activated carbon filters (aka activated charcoal filters) aren’t like traditional water filters. Instead, they consist of small, black beads or a solid black porous sponge that has undergone some additional processing to make it better at selectively trapping impurities. First, it is injected with heat, steam, or chemicals, which creates millions of small pores in the carbon, vastly increasing the size of the surface area. This activation process creates more pores for the carbon to trap and absorb a broader range of contaminants, making the carbon far more effective as a filter medium.

Each particle of carbon has a large surface area that gives the contaminants the maximum possible exposure to the active sites within the filter media so that more of the pollutants can be absorbed/removed. One pound (450g) of activated carbon contains a surface area of approximately 100 acres, which is almost three times the size of The Pentagon!

This and other remarkable properties of activated carbon make it a useful medium to eliminate impurities from water through adsorption. It’s also used to make respiratory masks, and used in air conditioning units and exhaust fans to rid the air of unwanted odors like smoke fumes, and animal odor.

How does activated carbon filters treat water?

activated carbon filter
SpringWell Water’s Activated Carbon Filter

Activated carbon filters treat water by using a process called adsorption. As the water passes through the activated carbon, the carbon acts like a sponge with a large surface area and absorbs the contaminants in the water. Simply, the activated carbon exerts a magnetic-like pull on the specific impurities and attracts and traps them in the pores of its surface area.

The dissolved impurities migrate from the liquid to areas in the pore channels with the most potent attractive forces. The contaminants are absorbed because the attraction of the carbon surface is much stronger than the attractive forces that keep them dissolved in the fluid. Following that, the filtered water flows to the next stage of filtration, if any.

As for chlorine and other chemicals that do not adhere to carbon, activated carbon filters use a chemical reaction to eliminate such pollutants. Activated catalytic carbon, which is more reactive than regular carbon, chemically alters the chlorine molecules, converting them into a chloride.

Are all activated carbon filters the same?

Activated carbon filters remove significantly higher concentrations of pollutants than regular carbon, but some of them have some slight differences. Some filters contain more or less activated carbon than others, which can impact their filtering capacity, the speed at which they absorb, etc. Besides, high levels of activated carbon extend the lifespan of a filter. Consequently, it will require fewer replacements and keep producing filtered water for longer.

Types of activated carbon filters


Activated carbon filters usually come in two main types: granular activated carbon (GAC) filters and carbon block filters.

GAC filters contain loose millimeter-sized granules of activated carbon that can detect and filter contaminants that would often go undetected in some other types of filters. The filter media used in these filters are usually coconut shell, coal, wood, and a few others, with coconut shell carbon being the most renewable.

GAC filters are perfect for water purification because:

  • They’re porous, inexpensive, and readily available for use as absorbents
  • They have more useful surface area per gram than any other material available for physical adsorption
  • They aren’t as restrictive as carbon block filters, thus allowing water to flow through the carbon at a faster rate
  • They last longer
  • The activated carbon can be re-activated, unlike the single-use powdered granules in carbon block filters

Despite all those excellent benefits, a significant issue with GAC filters is that the water can sometimes cut a path through the carbon and allow contaminants to pass through.

On the other hand, carbon block filters are made of finely powdered granules (usually 1 micron or less in size) and a binding agent that holds the granules together, so they don’t move about each other. The combination of the pellets and the binding agent is then heated and formed into blocks. Inside a carbon filter are three main types of filter media: bituminous coal, wood-based media, and coconut-shell media.

Carbon block filters provide 7 to 10 times more surface area than GAC filters and prevent channeling. However, the compact structure of the granules is likely to result in a lower flow rate, which may be an issue for some people.

What water contaminants do activated carbon remove or reduce?

Activated carbon filters do an excellent job of removing and reducing many different contaminants from water, including chemicals, gases, and physical impurities. Several studies cited by the Environmental Protection Agency in the United States (EPA) and NSF International claim that activated carbon filters eliminate between 60 and 80 chemicals from water, effectively reduce another 30, and moderately reduce an additional 22. Of course, the capacity of the system to remove or reduce those contaminants depends on two things:

  1. The type of activated carbon used (whether GAC or carbon block)
  2. The quality of the activated carbon

With that in mind, you must ensure that the filter you choose removes the problem-causing pollutants in your tap water. It might help to know that the EPA recommends activated carbon filtration technology as the only water treatment technology that eliminates almost all common and identified herbicides, pesticides, and inorganic contaminants in water.

Here are several classes of water contaminants that activated carbon filters work to remove and reduce:


Perfluorooctanesulfonic acid, or PFOS for short, is a water and stain-resistant synthetic compound that is widely used to make carpets, fire-fighting foams, furniture, paper packaging for food, clothing fabric, and other materials that are resistant to water, grease, or stains. PFOS chemicals are difficult to break down, so they can continue to exist in the environment and drinking water sources for decades. Exposure to PFOS over certain levels can result in adverse health effects, including congenital disabilities, cancers, liver effects, and more. Activated carbon filters are designed to effectively remove PFAS, including PFAS, PFOS, and PFNA.

· Pharmaceuticals

High-quality activated carbon filters can remove pharmaceutical residue in drinking water. The World Health Organization (WHO) defines pharmaceuticals as “synthetic or natural chemicals that can be found in prescription medicines, over-the-counter therapeutic drugs, and veterinary drugs.” These compounds can get into water sources through human waste from persons who have used the chemicals, uncontrolled and improper disposal of drugs (e.g., flushing drugs into sinks or toilets), and from agricultural runoff comprising livestock manure. When accumulated in the environment, pharmaceutical residues can significantly impact aquatic life. What’s even worse is that they can also leach into well water.

· Phosphate

Phosphate in drinking water comes from a range of sources, including runoff, human and pet sewage, chemical manufacturing, and others. Phosphate is crucial for healthy plant growth, but excess phosphate in water can result in a massive increase of algae, causing the water to become cloudy due to algal bloom. Premium charcoal filters usually remove up to 90% of phosphates in water.

· Chlorine

Chlorine is a popular water disinfectant in America. Almost every U.S. public water provider uses some form of chlorination to treat their water before distributing it to customers. Chlorine is added to destroy bacteria and other pathogens that make water smell and taste bad. But despite its remarkable disinfecting capacity, reports show that the risk for people who ingest chlorinated water is up to 93% higher than for those whose water does not contain the chemical. Thankfully, some activated carbon filters are excellent are eliminating chlorine and the unpleasant taste and smell that accompany it. Impressively, premium activated carbon filters can remove 95% or more of the free chlorine in some water sources.

· Chorine byproducts

Harmful chlorine byproducts, including THMs, VOCs, haloacetic acids, and others, can form when chlorine used to treat water reacts with the naturally present compounds in the water. Long-term exposure to some of these toxic byproducts has been linked to an increased risk of cancer, infant birth delivery problems, and other unwanted diseases and ailments. Activated carbon filtration is possibly the most effective technique used to eliminate chlorine byproducts from water. The EPA states that the technology removes the 32 most known chlorine byproducts, including the most common byproduct recorded in tap water reports: total THMs (TTHMs).

· Chloride

Chloride plays a significant role in chlorinating drinking water. But according to WHO, “Chloride concentrations above about 250 mg/liter can give rise to detectable [salty] taste in water…” On top of that, high levels of chloride can have adverse effects on human health, especially for people on low-sodium diets or those with certain health complications.

· Pesticides

Activated carbon filters are designed and tested to remove the 14 most common pesticides potentially found in water. These pesticides include Chlordecone (CLD/Kepone), Chlordane, Heptachlor, Lindane, and Glyphosate (Round-up). The National Institute of Environmental Health Sciences (NIH) defines pesticides as “any substance[s] used to kill, repel, or control certain forms of plant or animal life that are considered to be pests.” These substances include herbicides, insecticides, fungicides, and others. Because of the widespread use of these agricultural chemicals, they can easily reach water-bearing aquifers below ground. Pesticides can cause short-term adverse health effects, as well as chronic long-term health effects that can occur months or years after exposure.

· Herbicides

The use of herbicides has been a common practice in global agriculture for centuries, mainly to control unwanted weeds and increase agricultural production. However, when these chemicals are used in an uncontrolled manner, they sometimes end up in water sources and impact non-target aquatic organisms and even humans. Some herbicides can potentially cause cancers in humans, among other illnesses and ailments. Fortunately, activated carbon is tested and proven to remove 12 of the most common herbicides, including atrazine and 2,4-D weed killer.

· Lithium

Lithium is a naturally-occurring trace metal typically found in soil and other mineral formations, as well as in drinking water. Lithium in tap water is said to be a stress reliever and an antidepressant. Until more observational studies are done, we must consider the potentially harmful effects of the metal on human health. Charcoal filters reduce up to 90% of lithium in drinking water.

What activated carbon won’t filter

Activated carbon is most commonly used to filter water. It improves water quality, eliminates unpleasant odors, and removes chlorine and other pollutants. However, it’s not sufficient for eliminating certain toxic organic compounds, significant levels of metals, fluoride, or pathogens.

Without unique materials or additional filtration, activated carbon won’t filter:

  • Radionuclides
  • Most microbiological contaminants, including bacteria, viruses, cysts, coliform, protozoa, and other microorganisms
  • Significant amounts of heavy metals, copper, or iron
  • Inorganic pollutants like asbestos, and arsenic
  • Healthy minerals, such as calcium, potassium, and magnesium
  • Significant amounts of hydrocarbons or petroleum distillates
  • Dissolved solids, including minerals, salts, or metals, such as iron that aren’t usually considered contaminants

Should you use a carbon filter?

Deciding whether or not to use a carbon filter in your home and the type of filter you need all depends on the type(s) and contaminants’ concentration levels in your water. You can install one in case one or more of the toxic pollutants that activated carbon filters remove or reduce pop up uninvited in your water supply.

A home water quality test is a fast and reliable way to check your home’s water quality. These tests affordable, easily accessible, and display useful and easy-to-understand results quickly. Of course, we offer high-quality, affordable, and reliable water testing kits that test for many different contaminants in drinking water in just a few minutes.

Alternatively, you can contact your local water provider and request a copy of their annual water quality report, which usually provides useful information about the water quality in your area. Or if you want to take the more expensive, time-consuming, but more accurate-results-producing route, you can take a water sample from your home and send it to a laboratory in your area for testing.

Now, back to the question of “Should you use a carbon filter?” If your water quality test returns positive for any of the contaminants listed under “What water contaminants do activated carbon remove or reduce?”, then purchasing an activated carbon filter is a wise move. Again, you can also install one as a precautionary measure even if the tests return negative.

Should you decide to purchase and install an activated carbon filter, you have two main options:

· Point-of-entry (POE) filters

POE filters connect to the main water line entering your home. They treat all the water before it travels to your home’s water dispensers, such as faucets, toilets, showers, baths, kitchen, laundry, and others. The most common type of a POE system is a whole-house filtration system. Whole-house filters work to eliminate possible contaminants before they can reach your taps and ultimately be ingested or absorbed by the skin during washing, bathing, or showering.

The Springwell CF1 whole-house filtration system relies on the same POE technique and other unique materials and technologies to produce clean, great-tasting filtered water for your home. It uses catalytic activated coconut shell carbon, KDF media, and other innovative filtration methods and technologies to remove up to 99.9% of toxic water contaminants, including PFOS, PFOA, pesticides, chlorine, chloramine, copper, lead, herbicides, and many more.

The catalytic activated coconut shell carbon used in our whole-house systems is manufactured from high-quality coconut shells. This form of activated carbon significantly enhances the ability for superior efficiency when removing contaminants, and rapid decomposition of chlorine, chloramines, and chlorine byproducts.

Coconut shell activated carbon is the preferred carbon in POE systems, probably because it removes VOCs, THMs, hydrogen peroxides, hydrogen sulfides, TCE, PCE, detergents, phenols, taste, odor, and other contaminants from water. Plus, it is more environmentally-friendly than most other forms of activated carbon since the coconut trees are not destroyed during harvesting.

Apart from the impeccable filtration capacity of the CF1, it also produces an impressive water flow rate that helps to prevent decreases in water pressure. The system is easy to install and maintain. It also comes with a lifetime warranty, a six-month money-back guarantee, and free shipping!

· Point-of-use (POU) filters

POU filters are not to be confused with POE systems, though they do achieve somewhat similar results and are usually less expensive. POU filters are installed at a single fixture and treat water where it is being used – typically under the sink in the kitchen or bathroom.

Reverse osmosis systems are the most common type of POU system. These include units like Springwell’s SWRO-Nickel and SWRO-Bronze reverse osmosis systems, which can be installed under the sink. Both filtration systems can remove contaminants, such as lead, copper, fluoride, arsenic, aluminum, chlorine, chloramine, herbicides, pesticides, and many other pollutants, from water. Besides, they fit perfectly under nearly any size sink and provide 75 gallons of treated water to your home every day. They’re the perfect solutions if you want to treat the water at specific taps in your home.

Final Thoughts

Activated carbon filtration is an excellent water treatment method and technology. It solves many water-contamination issues that many of us have to deal with every day, but there are a few exceptions that you must consider.

Before you purchase an activated carbon filter, make sure to find out:

  • What specific contaminants it removes and reduces
  • The type of activated carbon the system uses (granular, carbon block, etc.)
  • What filter media it uses (e.g., wood, coconut shell carbon, coal, etc.)
  • The current state of your home’s water quality (use any one of the testing methods mentioned above)
  • Where in your home you need filtered water, whether in your entire home or specific points
  • Your budget
  • Other particular needs you might have

If you need assistance in finding a Springwell system that works for your filtration needs and your budget, please contact our friendly and supportive customer service team.