What Do Carbon Filters Remove From Water?

If you're concerned about the state of your drinking water, you may wish to explore water purifying options. Water filters, which can remove harmful contaminants and improve the taste and odor of your water, range from simple activated carbon filters to reverse osmosis systems, among others.

There are a variety of water filtration systems to choose from depending on the type of water you have (a private well or being part of a public city system are examples). The Centers for Disease Control and Prevention (CDC) details common reasons for employing a water filtration system; some of these include not liking the taste of your water, having hard water, being worried about bacteria or lead in your water or having arsenic in your water.

If you've decided to use a water filter, you'll need to choose one that best fits your water needs. The Environmental Protection Agency explains that activated carbon — the type of filter often found in refrigerators and pitcher filters is an activated carbon filter, according to the CDC — is used to absorb natural organic compounds, taste and odor compounds and synthetic organic chemicals in drinking water treatment. An activated carbon filter is also referred to as a charcoal water filter.

Another option is to use a reverse osmosis system to improve the taste of your water as well as to reduce levels of lead or other minerals. You may install a whole house filter or an under-sink filter for drinking and cooking water use.

Some harmful contaminants such as volatile organic compounds (VOCs) that can contaminate private wells can give water a bad taste and might smell like gasoline or other chemicals. There are many different kinds of VOCs with different health effects, including causing cancer, irritating the skin, affecting mucous membranes or damaging the nervous system, liver or kidneys, the CDC explains.

Water testing by a qualified lab will probably be needed to determine exactly which VOCs are present in your water. The CDC recommends using a point-of-entry filter system — where the water pipe enters your house — or a whole-house filter system to eliminate VOCs. This way you'll be able to have safe water for cooking and drinking as well as for bathing and cleaning. Activated carbon water filters can remove some VOCs.

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As the University of Nebraska notes, all water treatment methods have limitations, and a combination of treatment processes is often required to effectively treat water. Different types of carbon and carbon filters remove different contaminants and no one type of carbon removes all contaminants at maximum efficiency.

Activated carbon filters will not remove microbial contaminants such as bacteria and viruses, calcium and magnesium (hard water minerals), fluoride, nitrate and many other compounds. However, an activated carbon filter will remove organics that can affect the taste, odor and color of your water, and reduce chorine, THM, pesticides, industrial solvents, polychlorinated PCBs, PAHs and radon gases, North Dakota State University reports.

Some charcoal water filter side effects can occur when your activated carbon filter becomes loaded with organic contaminants or the filter is not used for a more than five days, North Dakota State University shows. The filter can become a food source for bacteria, and while the bacteria may not be harmful, some manufacturers have added silver to the activated charcoal to reduce bacterial growth. In addition, a bacteriostatic carbon filter is not adequate to treat water that is microbially unsafe.

And not all filters are created equal. A 2018 study by Ohio State University, published in the April 2018 issue of the journal ‌Water Supply‌, compared three popular pitcher brands' abilities to clear dangerous microcystins from tap water. Results showed that while one did an excellent job, other pitchers allowed the toxins — which appear during harmful algal blooms (HABs) — to escape the filter and drop into the drinking water.

The study did not name the brands involved in the research. But the two most effective pitchers had filters made of a blend of activated carbon sources while the least effective pitcher's filter was made entirely of coconut-based active carbon. In general, North Dakota State recommends using a high-volume activated charcoal unit to remove health-threatening contaminants.

If you are only concerned with taste, odor or color, pour-through and faucet-mounted units are most likely sufficient for improving water's taste, odor or color, although you will have to change the filter often. It's advised to have your water tested if you have any concerns and make a decision about using a water filtration system after receiving the results.

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