Carbon Block Water Filter vs Reverse Osmosis – Which to Choose?
Written by: Gene Fitzgerald // Last Updated: Jun 22, 2023
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Carbon block filtration and reverse osmosis are both viable options for filtering your household water.
Both have advantages and disadvantages, and it’s important to understand what you can expect from the two water filtration methods if you want to get the best performance for your money.
Here is a brief rundown of how both processes work and what they bring to the table.
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Key Takeaways
- Both reverse osmosis and carbon block filtration can be highly effective. One isn’t better than the other – it all depends on the type of water contaminants you are facing.
- Reverse osmosis excels at removing dissolved ions like heavy metals and salts.
- Carbon blocks are ideal for eliminating water disinfectants and their byproducts, bad taste and odor, and organic contaminants as a whole.
- Using a combination of the two works very well in most cases.
What Is Reverse Osmosis and How Does It Work?
Reverse osmosis is a process which forces water through a thin semipermeable membrane at a very high pressure. This forces water molecules to pass through the membrane, but pretty much everything else is unable to make it to the other side and stays behind. Those rejected contaminants get mixed with the waste water stream and sent away.
Simply put, reverse osmosis is highly effective against almost all types of water contamination and provides water of exceptional purity.
What Is Carbon Block Filtration?
Carbon block filtration, as the name implies, relies on blocks of carbon filter media that has been specially treated to make it as porous as possible. So-called activated carbon has a very high surface area with pores that adsorb contaminants.
Besides, the filtration qualities of activated carbon blocks tend to be many times better than those of regular granulated activated carbon. That’s because carbon blocks have a much higher density which means it’s harder for contaminants to slip through the filtering net.
Reverse Osmosis vs Carbon Block Filter – Differences
Reverse osmosis vs carbon block – what are the differences?
At their core, both processes are designed to filter water by running it through very tiny pores. However, the exact method of operation differs quite a lot between the two systems. It’s important to understand how they work if you want to ensure that you’re making a good investment in your household.
Filtration Process
As we mentioned above, reverse osmosis filtration works by forcing water through a thin RO membrane. The pores of this membrane are so small that only water molecules can diffuse through, with some minor exceptions.
On the other hand, carbon block filtration works by letting water run through compressed activated carbon. It might sound like a similar process, but the effectiveness of both approaches is very different.
It’s important to have your water properly tested so that you know exactly what kinds of contaminants you’re dealing with. Otherwise you might not get the results you expected.
Contaminants Removed
Reverse osmosis is great at removing many types of water contaminants, especially dissolved solids like salts and metals. It does lack in certain areas though, especially when it comes to dissolved gases.
On the other hand, carbon block filtration can be very effective at getting rid of dissolved gases and organic contaminants.
Using the two together allows you to get the best of both worlds.
Bad Tastes & Odor
Both filtration methods can improve the smell and taste of water. Carbon blocks tends to be slightly better in this regard.
But once again, this depends on the types of contaminants you have in your water supply and that are getting removed. Dissolved gases tend to affect the smell and taste of water more often than other types of contaminants, which is why carbon block filtration can be seen as more effective.
Water Turbidity
When it comes to improving water turbidity, this is another area where you could use either filtration method with good results.
However, reverse osmosis membranes tend to clog up fast when used on overly dirty water.
Organic Compounds
Organic compounds can be addressed by both systems pretty well. However, carbon takes the lead here. Carbon filtration tends to be much better at removing organic compounds. If your water analysis shows that you have lots of those types of contaminants, we recommend starting with a carbon block filter. Using a reverse osmosis system only makes sense if carbon doesn’t produce good results on its own.
Chlorine and DBPs
Carbon is great at removing chlorine and disinfection byproducts; reverse osmosis not so much.
Heavy Metals
Carbon can remove some types of heavy metals such as lead, but it’s generally not a good option for those specific contaminants. If you want to remove heavy metals primarily, you should focus on reverse osmosis filtration.
Microorganisms
Various types of microorganisms can be captured by a carbon block filter due to their relatively large size. However, that doesn’t apply to all microorganisms. Reverse osmosis filtration can be much better in this regard because the small pores on the membrane make it perfect for capturing pretty much all kinds of microorganisms, even viruses.
Dissolved Solids
Carbon doesn’t do a very good job at capturing dissolved solids. If those are your primary concern, you should go with using a reverse osmosis system instead.
Water Purity
If you’re primarily concerned about water purity in general, reverse osmosis will likely be the better option for you. It’s one of the best methods available on the market for purifying water, only matched by distillation in this regard.
With carbon filters, there are many variables in place that you need to consider, including the type of carbon, the micron rating of the filter, and how much carbon is used in the first place. You also need to consider the types of contaminants present in your water. All things considered, reverse osmosis wins this round.
Filtration Capacity
Carbon filters need to be replaced much more frequently than the membrane of a reverse osmosis system. As a general rule of thumb, you can expect to replace your carbon filter every 6 to 12 months. A reverse osmosis membrane can last much longer than that and needs to be replaced every two to five years. This all depends on the contaminants that you are removing, of course.
System Installation & Maintenance
There is a lot of variety on the market for carbon filters, so it’s hard to give an estimate of the overall complexity of installing one. If you’re buying something as simple as a water pitcher, that requires pretty much no installation other than taking it out of the package and assembling it. On the other hand, some types of carbon filtration systems can be much more complicated and time consuming in their installation.
Reverse osmosis systems as a rule tend to be more complicated and require some additional work in their installation. At the very least, you will need to make some additional plumbing connections (such as for the reject stream).
Cost
Reverse osmosis systems are more expensive. This may not always be the case if you want to buy a particularly advanced and comprehensive carbon filtration system. But it’s what you can usually expect. If you have more money to spend and your water is more heavily contaminated, investing in a reverse osmosis system is recommended.
Biggest Disadvantages
The main disadvantages of reverse osmosis include the fact that it wastes water and that it operates pretty slowly. Both of those can be addressed by upgrading the system in various ways. For example, you can reduce the amount of waste water by adding a pump.
With carbon filtration, the main drawback is the fact that it doesn’t remove as many different types of contaminants. You must also keep in mind that you have to maintain the system more frequently.
Further Reading:
Carbon Block Filter vs Reverse Osmosis – Which Is Better?
So, carbon block filter vs reverse osmosis – which should you choose? As is usually the case when choosing a home water filtration solution, it comes down to the types of contaminants you have in your water supply.
Even though reverse osmosis is much more thorough and effective by default, it doesn’t always have to be used. In some cases a carbon block water filter can be perfectly fine on its own.
Why Carbon Block Filtration and RO Go Well Together
If you have more advanced water filtration needs or generally want to improve the efficiency of your setup, you can use both solutions in combination. In fact, pretty much all reverse osmosis systems for home use come with carbon pre and post-filters these days.
This can be very effective for multiple reasons. The carbon filter can be a great barrier for protecting the reverse osmosis system from chlorine. On top of that, it can remove many contaminants that are not directly addressed by reverse osmosis.
If you have any questions about carbon block filter vs reverse osmosis please don’t hesitate to leave a comment below!
About the Author Gene Fitzgerald
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