Written by: Gene Fitzgerald // Last Updated: Jun 22, 2023
This page may contain affiliate links. If you buy a product or service through such a link we earn a commission at no extra cost to you. Learn more.
Carbon filtration and reverse osmosis are two of the most popular types of water purification methods available on the market.
They each work in unique ways and have their own advantages and disadvantages. It’s important to understand those differences if you are planning to invest in a system for your home.
So, carbon filter vs reverse osmosis – which is better?
Key Takeaways
Reverse osmosis is a water purification method which uses a thin semipermeable membrane through which water is forced at a high level of pressure. The membrane’s pores are so small that only water molecules can pass through, with everything else getting left behind and ejected. It’s a highly effective method of water filtration which removes pretty much all contamination.
Carbon filtration relies on passing water through activated carbon filter media, which is carbon that has been treated to expand its surface and make it as porous as possible. This makes it great at capturing various types of water contaminants including certain heavy metals, organic chemicals, and bad taste and odor.
Carbon filters come in several types, including ones that use activated versus catalytic carbon, and the filtration medium can be offered in a granular form or in solid blocks.
Reverse osmosis vs carbon filter media – both are very effective and can be great for household water purification. The differences are important to understand, though, especially if you’re dealing with specific types of contaminants.
The filtration process used by both systems is very different. As we mentioned earlier, reverse osmosis relies on pushing water through the RO membrane at a high pressure. Pretty much all impurities are being rejected.
On the other hand, carbon filtration relies on letting water pass through the filtering media, where contaminants get captured by inside the porous carbon.
Both approaches remove different types of water contaminants. Reverse osmosis is very effective in general, but it does have some limitations. Specifically, it doesn’t work well against dissolved gases and certain pesticides. Where reverse osmosis excels is removing dissolved solids like salts, minerals, and metals.
Carbon filtration can fill in those gaps, removing various contaminants that don’t get captured by reverse osmosis – think gases and pesticides. But, activated carbon doesn’t do a very good job eliminating dissolved ions. That’s why combining the two methods is so effective.
Both methods can improve the taste and smell of your water, but carbon filtration tends to be a bit better in this regard. That’s because many of the causes of bad taste tend to be linked to organics, dissolved gases, and similar contaminants. Still, you can usually see some improvement in this regard with reverse osmosis alone.
Turbidity is something else that can be improved equally well by both filtration methods. It’s just that a reverse osmosis membrane will clog up fast if used on overly dirty water.
You can get rid of organic contaminants well enough with both filtration systems. However, if this is your primary concern, we recommend focusing on carbon filtration. Reverse osmosis can still be very effective in this regard, but you have to be careful about the exact types of organic contaminants you have in your water.
This is another area where the two filtration methods somewhat overlap, but carbon comes out on top for the most part. If you’ve got lots of chlorine and disinfection byproducts in your water supply, we recommend a combined approach.
Activated carbon is capable of removing some types of heavy metals including lead, but it’s not the best type of filtration for that. If this is your primary concern, you should focus more on using reverse osmosis.
Microorganisms come in different sizes and can be captured with various levels of efficiency by carbon filtration. On the other hand, reverses osmosis modules can effectively remove pretty much all microorganisms from your water supply.
It’s hard to beat the performance of reverse osmosis when it comes to removing dissolved solids from your water. Carbon filtration might have some minor effect in this regard, but it’s not really intended for this.
Depending on the type of activated carbon you’re using, specifically whether it’s granular or block, as well as regular versus catalytic carbon, you can achieve varying water purity levels.
On the other hand, reverse osmosis removes pretty much all contaminants, which gives you water that’s as pure as it can get.
In both cases you need to perform some maintenance on the system to keep it running in the long term. Carbon filters must be exchanged much more frequently. Usually, you should anticipate replacing filters every six to twelve months.
With reverse osmosis you need to replace the membrane, but this can be done much less often. With most systems, the membrane can last at least two years, and in some cases even up to five.
Reverse osmosis systems tend to be a bit more complicated to install as they require some extra work. Specifically, you need to hook up a drain connection and a plumbing connection.
Carbon filtration systems, on the other hand, are quite varied in their designs, and some of them are pretty simple to install, while others are much more complicated. At the very low end of the complexity spectrum, you have things like pitchers, which require no installation at all.
Reverse osmosis systems are more expensive by default, all things considered. If you’re on a limited budget, you might want to go with a carbon filter, at least in the beginning. See how it works out for you, and if you’re still not satisfied with the overall performance, you can look into switching to a combined system down the road.
Both systems have their disadvantages that are important to consider as well. With reverse osmosis, this is mostly about water wastage. The purification process tends to waste a lot of water, especially if you’re using a more basic system without additional pumps. You may end up wasting as much as 80% of your feed water during the filtration process.
The main drawbacks of carbon filtration include its relatively low effectiveness with some types of contaminants and the low spectrum of contaminant types addressed. It also has a shorter lifespan than reverse osmosis, requiring more frequent filter replacements.
So, activated carbon filter vs reverse osmosis – which is better?
There is no inherently better solution between the two. It all comes down to what kinds of contaminants you’re dealing with and in what quantities. For some people, using carbon alone can be perfectly fine. In other cases, reverse osmosis is the only solution that works.
Besides, more or less all reverse osmosis systems for home use come with at least 1 carbon pre-filter and 1 carbon post-filter, so that you get the best of both worlds.
Reverse osmosis and activated carbon work very well in combination. Carbon filters can protect the reverse osmosis membrane from chlorine, which can damage it significantly. It can also remove various contaminants which reverse osmosis might not address, including various types of pesticides and dissolved gases. In the end, the decision comes down to analyzing your water supply and figuring out what kinds of contaminants you need to address.
If you have any questions about reverse osmosis vs carbon filter please don’t hesitate to leave a comment below!
About the Author Gene Fitzgerald
Information provided on BOS is for educational purposes only. The products and services we review may not be right for your individual circumstances.
We adhere to strict editorial guidelines. Rest assured, the opinions expressed have not been provided, reviewed, or otherwise endorsed by our partners – they are unbiased, independent, and the author’s alone. Our licensed experts fact-check all content for accuracy. It is accurate as of the date posted and to the best of our knowledge.
If using both pressed carbon block filter AND a RO system, which should be first in the order of filtration?
ReplyCarbon! Because it removes any chlorine which could damage the RO membrane.
Reply