Carbon Filters vs. Reverse Osmosis: Which is Best Water Filter for Your Home?
A home water filtration system could make a huge difference in your house or apartment, whether you’re using it for drinking water or water you use for other purposes.
But choosing one for your home isn’t as easy as you’d expect, is it?
Search “water filter” or “reverse osmosis system” online and you’ll get literally thousands of different results: whole house units, point-of-use filters, 1-stage to 8-stages, and so on… But of all the types of softeners you’ll come by, you’ll come by two main water filter types: reverse osmosis and carbon filters.
Carbon filters, for the most part, are pretty simple systems that do a great job at capturing chemical impurities in water. Reverse osmosis not only helps capture those same impurities but heavy, toxic metals, too. Both types of water softeners are great for home use, but not every system is made for everyone. That’s why in this article we’ll be breaking down the benefits and drawbacks of carbon filters and reverse osmosis to give you a better idea of which water filter is best for your needs.
Carbon Filters
Carbon filters, also known as “carbon block” filters, use a special carbon medium (usually coconut shells or charcoal) to help adsorb molecules, atoms, and ions in the water it filters. Adsorption, unlike absorption, is when unwanted particles stick to the surface of the medium. The media surrounding the carbon lets water pass through while holding certain particles back, and because it is only a 1 to 2-part system, the water comes out to you pretty fast.
Adsorption keeps compounds like chlorine, mercury, dioxin, formaldehyde, pesticides, herbicides, chlorine, and solvents stuck to the carbon. Unlike absorption that would push particles into the carbon, adsorption keeps particles trapped to the carbon’s surface. That helps keep more harmful gasses and liquids out of your drinking water (Note: absorption could actually result in higher concentrations of harmful particles in that same water due to faster carbon deterioration).
Carbon filters are so popular because anyone can install, use, and maintain one. From simple water bottles like the Aquasana Plastic Clean Water Bottle to a one-stage water filter like the NU Aqua 1 Stage Countertop Water Filtration System, there are no special skills needed to set up one of these systems. They’re also cost-efficient, with the most expensive systems coming in around $50– easily $150 less than the most basic reverse osmosis system. That’s something else everyone can love. However, this simplicity comes at a cost.
As the old saying goes, you get what you pay for, and that’s definitely true for carbon filters. When you need to filter heavy metals like iron, lead, cadmium, and aluminum; or dissolved solids like sodium, calcium, magnesium, and inorganic minerals, carbon filters won’t do the trick. They also don’t work against bacteria and viruses, so if you need heavy duty filtration, a carbon water filter won’t work.
You’ll also need to keep a close eye on carbon filters because they’ll need more filter changes than RO systems. Unlike RO systems with multiple stages, a simple carbon filter takes more direct ware on its parts. To that, carbon wears and creates channels- like little veins- that let water go passed unfiltered which will contaminate the water you want to filter. Because all this wear happens directly to the filter relatively fast, carbon block filters tend to wear out pretty quickly and thus need a lot more changes than RO’s.
How Does Charcoal Filter Water?
Carbon filters use carbon charcoal usually sourced from coconuts. This material is very porous and helps filter water by absorption.
Since the carbon is extremely porous the chemicals and impurites bind to the surface of the charcoal. Over time as more of the pores in the charcoal collect contaminants it becomes less effective and requires replacement. Fortunately charcoal carbon filters are inexpensive and easy to replace.
How Long Does A Carbon Water Filter Last?
A carbon water filters life span will vary depending on the type of carbon used, the amount carbon inside the filter, and the usage.
Carbon filter typically come in two forms, granular and block. Granular carbon filters have an extremely high surface are beacuse the carbon is broken into small granules. Carbon block filters are comprised of a block of compressed carbon that is highly effective at contaminant removal. This is because the water is require to pass through the compressed carbon.
The size and amount of the carbon used in the filter plays a large role in the lifespan. The large the filter, the more surface are to absorb contaminants. Once the pores in the carbon become full it's time to change the filter. This is why a larger carbon water filter has a longer lifespan.
Lastly, the amount of usage is what plays the biggest factor. If you are constantly using the filter it's life will be much shorter than if your filling up just a glass or two a day. Most carbon filters last approximately 6-12 months depending on size and usage.
Interested in a carbon filter?
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Reverse Osmosis Systems
If you thought carbon filters got rid of a lot of contaminants, reverse osmosis gets rid of even more. Reverse osmosis systems are known for being heavy-duty water filter systems, and we’d say that’s a pretty accurate statement.
With reverse osmosis, water is pushed through multiple filters that keep a range of unwanted elements from reaching your drinking water. Between the multiple filters of an RO system, you’ll filter about 95-99% of all dissolved salts, bacteria, and heavy metals like lead, mercury, calcium, iron, and asbestos. They also get rid of elements any carbon filter gets rid of like chlorine and mercury.
In fact, there are at least 1-3 carbon block filters in any given RO system to help make water as clean as possible. The NU Aqua Platinum Series 5 Stage 100GPD RO System, for instance, has pre-carbon, carbon, and carbon polishing filters with a range of carbon mediums and consistencies to filter as many harmful particles out as possible. An RO water filter can do up to triple the work a stand-alone carbon filter can.
But reverse osmosis systems sometimes do too good of a job at filtering your water. Sounds weird, right? But it’s true.
RO systems filter out lots of minerals which is great against hard water, but we actually need minerals like calcium, sodium, and magnesium in our diets. When our water doesn’t contain some of those minerals we need to supplement them in our food, which can be difficult if we don’t have access to the foods that contain those minerals. So while it’s great to get minerals out that make your water too hard, remember that it’s only the concentration of minerals- not exactly the minerals themselves- that are the issue, so use reverse osmosis filters carefully.
Not all the water that’s filtered through an RO water softener reaches your tap, either. Unfortunately, only about 60% of the water filtered by reverse osmosis gets to your RO tank, with the rest of the “waste” water (the 40% of water with all that bad stuff) going down a separate waste line. While this is super helpful in getting good water to you, you don’t have as much fresh water at your disposal as a carbon filter lets you have.
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So which filter is better: Carbon Block or Reverse Osmosis?
Carbon block filters and reverse osmosis systems are both fantastic water softeners, and great at the jobs they perform. As you could imagine from reading this article, there’s a time and place for each type of water softener we’ve talked about. While we don’t believe one type is better than the other, we definitely know each water filter style has its pro’s and cons.
Reverse Osmosis systems are great for homes and heavy-duty water filtration. If you need an intense water filter system to get ride o bacteria, metals, and even parasites from well water as well as treated tap water, RO is the water softener for you. Just keep an eye on minerals levels because RO will filter lots of helpful minerals, and if there are too many minerals filtered out you’ll need to supplement them.
Carbon filters are great for single-use needs. Some people are happy with the purity of their tap water (i.e. % of TDS’s in water) and just want to improve the smell or taste of it. Others are happy with their drinking water but need softer, better smelling water in their shower. Usually, smell and taste are due to minerals that carbon filters do an excellent job of getting rid of. When you only need clean drinking or showering water there’s no need for an entire RO system. With a carbon filter, you’ll get all the water you need and get it right away.
In conclusion, carbon filters and reverse osmosis water softeners are both awesome water filters. Reverse osmosis is great for hardcore water filtration for smell, taste, and safety; whereas carbon filters work great for simple tasks like making water smell and taste a little better.
