Activated Carbon and Water Filters
Getting rid of Organic Solutes
There are two mechanisms by which activated carbon removes contaminants from water. The first one is called adsorption, which is not to be confused with absorption. The second one is called catalytic reduction.
Adsorption vs Absorption
Since the spelling is very similar people often confuse these two terms. When you clean up some spilled water with a paper towel, the moisture is absorbed, and travels inside the actual structure of the paper fibers. That doesn’t happen with activated carbon.
Activated carbon uses adsorption, a principle which is much more like flypaper because unwanted chemicals stick to its surface. When a housefly gets close to flypaper, the color, odor, and shininess draw it in, and when it lands it becomes permanently stuck on the surface. Activated carbon attracts the nasty organic compounds, too, and because it has such a large amount of surface compared to its size, it can repeat this action millions of times.
This reaction is less important to us. This is the method by which activated carbon reduces chlorine-type compounds in the water. But as you will see below, our filters are designed in such a way that those compounds are completely neutralized before they get to the carbon filter. By not using this capability, it extends the functional life of the activated carbon filter.
Why use an activated carbon filter?
Chlorine is a well-studied, well-understood, and well-tolerated disinfectant used to kill pathogens in the water supply. CBPs (Chlorination By-Products) such as trihalomethanes (THM) have been identified as possibly being carcinogenic, but that has not yet been proven.
Some 20% of municipalities have been experimenting with chloramine as a substitute to meet the EPA guidelines for reduced CPBs, primarily because it is very inexpensive. There are many methods to reduce CPBs, the simplest of which is pre-filtering out organic matter so that the chlorine has nothing to react with.
Chloramine has been linked to leaching of lead from old pipes, and increasing lead exposure, which particularly affects children and their mental development. More importantly, very few studies have been done on how chloramine affects respiratory, skin, or digestion in human beings of any age. Municipalities are now searching for alternative methods to reduce CPBs that are safe for humans. Chlorine is back in fashion because it is well understood.
Information like this just makes it that much more important to eliminate chlorine and the CBPs which accompany it. In countertop water filtering pitchers, typically you will find that activated carbon is the go-to solution. When used for low-volume, cold water treatment, it works very well, provided you change the filters regularly.
Granulated Activated Carbon
Granulated Activated Carbon (GAC) filters can remove 70-90% of chlorine from water, but they have a limited capacity to do so. They tend to clog and fail particularly quickly in hot water (such as your shower) when exposed to chlorine.
GAC’s greatest weakness is that it is most effective and durable only in cold water; hot water quickly exhausts its effectiveness for chlorine, so water is best dechlorinated before it gets to the carbon element.
For this reason the water (in our filters) always passes through an insoluble pellet bed of calcium sulfite first, which converts 100% of the free-chlorine into harmless, non-toxic materials (chlorides) that are safe for humans. This considerably extends the life of the GAC filter, allowing it to do the job it is truly best suited for.
One of the GAC’s greatest strengths is its ability to remove dissolved organic chemicals such as pesticides, fertilizers, hydrogen sulfide (that rotten egg smell), dissolved drugs (leftover pharmaceuticals that people have flushed down the toilet instead of returning to the drugstore for proper disposal), and strange tastes or odors.
GAC filters are particularly effective because of a characteristic they possess called microporosity. Just 1 gram of activated carbon, or about 1/28th of an ounce, has a molecular surface area in excess of 32,000 ft2, or 3,000 m2. How big is that? It is the equivalent of more than 11 doubles-tennis courts, or an NHL hockey rink—a truly massive area. Organic chemicals are attracted to the surface of the activated carbon and are permanently trapped.
What It Won’t Do
While activated carbon filters are stunningly effective when they are used to remove Volatile Organic Compounds (VOCs) and sediments, when it comes to inorganic compounds, they don’t do very much at all. By definition, organic compounds are those that contain carbon.
Carbon has an affinity for carbon, hence the reason that we use an activated carbon filter. If you were to take a volume of saltwater and put it through a water filtration pitcher it would still be saltwater.
Really Easy Chemistry
Salt is composed of two different atoms bound closely together. Separately, these two substances are toxic to human beings, but when they connect they become harmless table salt. They are sodium (Na) and chlorine (Cl) and together make NaCl (sodium chloride). As you can see, there is no carbon (C) so it will just pass right through the filter, unaffected.
This is the reason we use multistage filters. Each individual segment has its specialized job to do.
Now you know the secret of how activated carbon removes those strange flavors and smells, and how it protects you from dermatitis and dandruff because of undesirable chemicals like chlorine and its byproducts.
There are just a couple more things you need to know. Right now there’s a new fad coming from manufacturers in Japan and Korea. They are making shower filters loaded with vitamin C (ascorbic acid/sodium ascorbate).
They point out that it is the most effective way to remove chloramine from the water supply. While true, the odds are 80% that your water is treated with chlorine, so that expensive solution is not for you. You do not want to be replacing those cartridges every month, especially if you don’t have chloramine. If you contact your water utility and ask, they’ll tell you whether you have chlorine or chloramine treated water.
Vitamin C does indeed reduce chloramine in your shower water, but it doesn’t remove any of the other volatile organic chemicals. The other problem is that the vitamin C cartridge dissolves over the course of time, and there’s no way to tell that it is exhausted—that the vitamin C is all gone.
The last consideration is that the human body is normally a little bit alkaline when we’re completely healthy. Vitamin C is an acid, and you should ask yourself if you want to be showering in acidic water.
We are big fans of real science here. We don’t need to scare you to make you use our products; and we don’t need to deceive you so that you don’t use someone else’s product. We just tell you the truth, because we believe you are smart enough to make your own good decision!
If you live in an area with over-chlorinated water and other undesirable contaminants (as most of us do), please feel free to look over our exceptional selection of high quality filtration products. We’re more than happy to answer any questions you may have. Just click here to go directly to our online contact form and we’ll get back to you within 24 hours!
Whether you’re interested in high quality fixed or handheld shower heads, shower filters, or bidets, we’re here to help you make your water better!