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Reverse Osmosis vs Carbon Filter

If you’re dealing with poor tasting, cloudy looking  and funky smells, you’re probably looking for an easy solution to your water problem. When searching for the right water filtration system, you’re almost guaranteed to come across these two popular options: reverse osmosis unit and carbon filters.

The most common types of water filters, reverse osmosis and carbon filtering both offer a way to  treat your drinking water but yield different results.

Does reverse osmosis remove minerals? The short answer is “yes.” And as for carbon filtration? Unfortunately, that’s a “no.”

However, there’s a lot more to understand when it comes to mineral filtration and reverse osmosis. In this guide, we’ll go deep into minerality, the fundamentals of filtration, and the way to determine the best drinking water systems for your situation.

The Fundamentals of Water Filtration

We’ve touched a little on water filters vs reverse osmosis, but it’s important to grasp the fundamentals of water filtration as well.

Before diving into these two methods in more detail, you need to understand some basic facts about water filters: 

  • How Do Water Filters Function?  –  Filters use chemical, biological, or physical processes to remove harmful contaminants from water. Contaminants can include everything from microbes and bacteria to debris and dissolved minerals commonly found in groundwater. 
  • What are POE and POU? – Point-of-entry (POE) refers to filtration systems attached at the point where the water enters your home or business from the municipal water source. Point-of-use (POU) refers to systems attached to faucets, showerheads, or water pitchers. POE and POU systems offer different advantages depending on your filtration needs.

These facts apply to both reverse osmosis and carbon filters.

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Reverse Osmosis 101

A reverse osmosis filter is a great option if you want to filter out every possible contaminant in your water.

While reverse osmosis certainly sounds like a topic from biology class, it’s perfectly understandable when broken down into a few steps.

Reverse Osmosis or RO is a physical filtration process involving a semipermeable membrane typically made of cellulose acetate, polysulfone, and polyamide. The reverse osmosis membranes are solvent resistant, meaning they won’t be damaged or made less effective by water. 

RO, in its simplest terms, works like this: 

  • Unfiltered Water Enters The System – Whether it’s a POE or a POU system, the first step is getting the water source flowing through your RO system.
  • Water Passes Through The Semipermeable Membrane – Through the use of applied pressure, the source water is forced through the membrane. The molecules of the mineral contaminants are larger than the water molecules, meaning those larger molecules are left on the pressurized side of the membrane while purified water moves through it.  
  • A Solute and a Solvent Remain – After adequate pressure has been applied, you’re left with a solute (a brine of wastewater and filtered contaminants) and a solvent (purified water).

In short, the reverse osmosis membrane acts like a bouncer at an exclusive club, water is the VIP, and contaminants are not on the guest list.

What Does Reverse Osmosis Remove?

The process of reverse osmosis has been popular for more than 50 years and was invented more than 100 years ago. Over the course of several decades, reverse osmosis technology has been refined to filter smaller and smaller ions—we’re talking filters with a pore size of .0001 microns.

In case you don’t know how small a micron is, the diameter of a single human hair is on average about 70 microns. So, .0001 microns is quite literally microscopic.

That means a reverse osmosis system can filter out minerals, dissolved solids, and much, much more.

A modern Reverse Osmosis filter is capable of filtering out:

  • Protozoa 
  • Heavy metals
  • Microorganisms including viruses and bacteria
  • Fluoride
  • Some hydrocarbons

Most importantly, for this guide, RO filtration is the best way to make sure your water is mineral-free. In a 2009 study, it was shown that “Reverse Osmosis (RO) removed more than 90-99.99% of all the contaminants including minerals from the drinking water supply.”1 

Minerals just can’t make it past the membrane.

What About Carbon Filtering?

As we mentioned earlier, you most likely stumbled across carbon filtering when researching water filtration options. You may even already own a water pitcher with a charcoal filter, or have one attached to your sink. You might be asking, is this capable of removing minerals as well

Unfortunately, the answer is no.

What you’re looking at is a carbon filter, one of the most common types of water purification and filtration systems for residential use, and likely the method you’re most familiar with. After all, carbon POU filters are affordable and can certainly improve taste.

Despite its commonality, carbon filtering is not always ideal, though it’s important to know why.

Carbon filtering involves the use of Granular Activated Carbon or GAC. GAC is made from oxygenating carbon to create a highly porous, black material with a large surface area. Water passes through the carbon particles, which filter out impurities and contaminants.2

Activated carbon filters out:

  • Chloramine
  • Tannins
  • Chlorine and chlorine byproducts
  • Hydrogen Sulfide 
  • Most Pesticides and Herbicides
  • VOCs (Volatile Organic Compounds)

What Carbon Filters Leave Behind

Because some water may remain in the filter, GAC filters require cleaning and replacement. If left unattended, the stagnant water has the potential to grow bacteria which is not only a little gross but a potential health risk.

It’s also important to be aware of what activated carbon doesn’t filter, including:

  • Minerals
  • Nitrates and Nitrites
  • Large amounts of heavy metals
  • Microorganisms including viruses and bacteria
  • Fluoride
  • Some hydrocarbons

GAC is highly effective for some materials, but smaller molecules can pass through it. While carbon filtering is a sensible choice for some filtration needs, it ultimately isn’t the best option if you’re looking to remove minerals from your drinking water. 

Hard Water, Simple Science

The facts are simple: if you want to remove minerals, only an RO water filter will do.

So, is minerality really the source of your water woes? To make a decision, you’ll need to understand water hardness.

Determining the hardness of water might sound like figuring out the wetness of sand, but don’t fret, hard water simply refers to water with a high concentration of minerals in it.

  • The most common mineral contaminants in drinking water are Calcium and Magnesium. Typically, these are found in groundwater that has percolated through layers of chalk, gypsum, or limestone.
  •  The water is a solvent (meaning it dissolves substances) and leeches out relatively small particles of minerals from the larger deposits, effectively becoming contaminated.

Water hardness is determined by a ratio of milligrams of calcium carbonate to liters of H20.3

  • 0-60 mg/L is considered soft
  • 61-120 mg/L is considered moderately hard
  • 120-180 mg/L is considered hard
  • Above 181 mg/L is considered very hard

If you’re staring at a glass of tap water trying to determine the level of hardness, you might have a hard time figuring it out. The mineral content of your drinking water is typically invisible to the naked eye, though sometimes you can see a slight discoloration. 

There are a few ways to test water hardness, but most often it’s easily detectable by taste, touch, or smell.

The Problem With Minerals

It’s important to note that mineral contaminants in your drinking water do not pose a serious health threat.

That said, they often do:

  • Create an Unpleasant Drinking Experience – Most people want a glass of water to be thirst-quenching, refreshing, and essentially tasteless. When drinking hard water, you’re likely to taste the mineral impurities, resulting in a bitter or even salty flavor. In addition, the smell from hard water is often compared to rotten eggs making for a less than ideal glass.
  • Leave Stains or Deposits – Limescale build-ups from hard water are fairly common. The mineral content of the water leaves a residue on sinks, floors, and just about anything else that might get wet. It can also pose a problem for laundry, leaving stains on clothes or requiring more detergent for a proper wash.
  • Cause Dryness and Irritation – Mineral contaminants can affect the pH balance of your tissues, leading to dry skin, brittle hair, and dandruff. If you have sensitive skin or an already dry scalp, hard water can be a major discomfort.

If these issues sound familiar, an reverse osmosis system is the best option to safeguard your water.

From Hard to Easy

If you’re tired of funny tastes, spotted silverware, and stains on your clothes and fixtures, it’s time to consider a water softener or a reverse osmosis water filtration system. Experts agree you should be drinking 2-4 liters per day, so why settle for less than excellent?4

There are certainly a lot of benefits to reverse osmosis at a personal and a commercial level, and with the right system, you could be pumping gallons of clean, great-tasting water in no time.

Rayne Water: The Bouncers For Your Personal Water Supply

Now that you know a little about Reverse Osmosis process and its mineral filtration abilities, it’s time to put a plan into action, get your feet wet, and dive right in. A reverse osmosis water system provides better water quality, free of harmful contaminants and minerals.

If you’re looking for a smart solution to your water filtration issues look no further than Rayne Water. We’ve been providing water systems to individuals and businesses for over 90 years, and can match you with your perfect system to keep unwanted particles out of your home for good. 

Contact Rayne Water today to schedule a water test. We’re here to help provide the purest water for every situation. Check out our products and services, learn more about RO filtration, and remember to stay hydrated!


  1. International Water Association. Reverse osmosis and the removal of minerals from drinking water.
  2. Thought Co. Activated charcoal and how it works.
  3. USGS. Hardness of water.
  4. Mayo Clinic. Water: how much should you drink every day.
  5. FDA. Reverse osmosis.
  6. International Water Association. Reverse osmosis and the removal of minerals from drinking 
  7. water.
  8. Thought Co. Activated charcoal and how it works.