What Is the Use of a Post-Carbon Filter in an RO System?
Written by: Alexandra Uta // Last Updated: Jun 22, 2023
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A reverse osmosis system has so many filtration steps and options for various add-ons you might wonder, are they really all necessary?
For example, what about this post-filtration carbon filter? If my water is already filtered as well as they say it should be, why do I need this?
What is the use of a post-carbon filter in an RO system? Let’s find out!
Contents
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Key Takeaways
- A post-carbon filter in an RO system is usually the final step in filtration and mainly ensures your water is free of any strange tastes or smells before you dispense it from the faucet. It’s like a final polish.
What Is the Use of a Post-Carbon Filter in an RO System?
A post-carbon filter in a reverse osmosis system is essentially there to polish your filtered water. It is usually the last stage of filtration and will take care of any strange tastes or smells that your water may have picked up from sitting in the storage tank.
Essentially, after the water has diffused through the RO membrane, it is so pure that it has a much higher affinity to absorb impurities. So while the water is stored in the RO tank, it may leach plastic from the tank’s air bladder. Thus, before the water finally comes out of the RO faucet, a carbon post-filter between faucet and tank will remove any residual plastic taste and odor – like a final polish.
Also, a post-carbon filter will also deal with any remaining pollutants, such as chlorine and volatile organic compounds.
How Does Activated Carbon Filter Water Contaminants?
Activated carbon has a very large surface area, resulting in exceptional adsorption properties. This enables the capture of various water contaminants. Activated carbon filters water by trapping the pollutants in the carbon’s porous surface.
Numerous carbon filter types exist, each with unique advantages and disadvantages.
GAC vs. Carbon Block Filter
The two primary categories of carbon filters are granulated activated carbon (GAC) and activated carbon blocks (ACB). Both types function based on the same core principle, but GAC filters offer smoother water flow due to less obstruction. Carbon filter blocks on the other hand remove more suspended particles due to their smaller pore size.
Catalytic Carbon
Catalytic carbon filters are specifically designed to target chloramines. Additionally, they can eliminate other contaminants that conventional carbon filters may not effectively remove, such as hydrogen sulfide.
Charcoal vs. Coconut Shell Carbon
As the names suggest, coconut shell carbon is derived from coconut shells, while charcoal carbon is made from charcoal. Coconut shell carbon has a higher micropore density, enabling it to adsorb a broader range of contaminants.
What Contaminants Are Being Removed?
Activated carbon filters are capable of eliminating numerous impurities from water. Some of these include:
- Volatile organic compounds
- Sulfur
- Chlorine byproducts
- Waterborne pathogens (dependent on the filter’s micron rating)
- Pesticides
- Herbicides
- Chlorine
However, there are certain substances that carbon filters cannot remove from water, such as:
- Minerals
- Dissolved inorganic substances, for the most part
- Fluoride and other salts
- Some heavy metals
Further Reading:
Does Activated Carbon Reduce Water Hardness?
Activated carbon is not designed to reduce water hardness. By default, it may remove some of the water scale if the particles are large enough to be trapped, but that is not the norm. You are better off with water softening or reverse osmosis to reduce water hardness.
How Often Should Post-Carbon Filters Be Changed?
It really depends on your water quality and how much you are using per day, but most post-carbon filters are rated between 12 and 24 months. If you notice changes in the taste or quality of your water, this may indicate that one or more of the filters needs to be changed.
If you have any questions about the use of a post-carbon filter in RO please don’t hesitate to leave a comment below!
About the Author Alexandra Uta
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