Water Softener vs Reverse Osmosis System: Differences + Which Is Better?
Written by: Alexandra Uta // Last Updated: Apr 28, 2023
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Water softeners and reverse osmosis systems sometimes get mixed up by people without too much experience in the area of water treatment.
In reality, even though they might seemingly share some functionality, they are completely different.
This includes their intended application as well as the way they operate. Learn more below.
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Key Takeaways
- There’s no “better” option when it comes to choosing between a water softener and a reverse osmosis system. Both are designed to address entirely different problems, and work in different ways.
- Water softeners remove minerals from hard water making it soft.
- Reverse osmosis systems remove potentially harmful contaminants from drinking water.
- Using the two in combination can make a lot of sense.
Water Softener vs Reverse Osmosis System – Which Is Better?
First of all, water softener vs reverse osmosis system – which is better?
Comparing water softeners and reverse osmosis systems in terms of “which one is better?” makes pretty much no sense. Both systems have entirely different intended applications, and they work in very different ways.
In fact, it’s not rare to see the two systems running alongside each other when water needs to be treated for both contaminants as well as hardness. But it’s also perfectly possible to use just one without needing the other.
What Is a Water Softener and How Does It Work?
The purpose of a water softener is to remove or reduce water hardness:
As hard water passes through the device, hardness minerals are attracted by the small beads in the resin tank. The minerals are exchanged for sodium or sometimes potassium ions which go into solution. Afterwards, soft water makes its way out of the water softener and into your plumbing. It will have most of its hardness minerals removed.
As time goes on, more and more hard water minerals accumulate in the softener’s resin bed. At one point, it’s saturated and needs to regenerate. The water softener backwashes its resin tank to flush out all hardness and refreshes its resin with new salt from the so-called brine tank which is like a salt storage. Once regenerated, the water softener switches back to normal operation.
By the way, water softeners are usually installed at the point of entry, meaning they provide soft water to the entire house protecting plumbing and appliances.
What Is a Reverse Osmosis System and How Does It Work?
A reverse osmosis system is a water filter. It’s intended purpose is to remove harmful contaminants and those affecting water aesthetics in order to provide healthy and safe drinking water.
Most RO systems get installed at the point of use, meaning a single outlet such as your kitchen sink. But there are also whole house RO systems. These are mainly used if your water supply is heavily contaminated and reverse osmosis is the only way to get rid of all the various contaminants which could not only harm your family but also your pipes, washer, water heater, etc.
Reverse osmosis systems are mechanically pretty simple. The basic idea revolves around forcing water through a thin, semipermeable membrane at a high pressure. The membrane’s pores are small enough that only water molecules are allowed to pass through. All other contents of the input water – in other words, all contaminants and impurities – get rejected and flushed down the drain in a separate stream.
What’s the Difference Between a Water Softener and a Reverse Osmosis System?
As you can see, water softeners are fundamentally different from reverse osmosis systems. Both work in different ways and are designed to address different issues.
Difference #1: Intended Purpose
A water softener is designed to soften water, as the name implies. It doesn’t do much to address contamination of your water.
On the other hand, a reverse osmosis system is specifically designed to remove contaminants. The fact that a reverse osmosis system can also remove minerals might be what leads to some people’s confusion. It’s important to know, though, that a reverse osmosis system should never be used for the purpose of softening water, unless you don’t mind frequent membrane replacements at additional costs.
Difference #2: The Treatment Process
Reverse osmosis vs water softening – the two processes work very differently as well.
Water softeners rely on a cation exchange resin to do their job. The resin is made up of smalls beads supersaturated with salt ions. As hard water minerals stick to said beads, the salt ions go into solution.
On the other hand, the main component in a reverse osmosis system is the semipermeable membrane. Its pores are so tiny that pretty much everything except water gets rejected.
Difference #3: Impurities/Contaminants Being Removed from Water
Water softeners do remove some contaminants from water, but the process specifically targets minerals. These include calcium (Ca2+) and magnesium (Mg2+) ions, as well as iron (Fe2+ or Fe3+) and manganese (Mn2+ or Mn3+) to some extent. Those minerals are not necessarily harmful in small amounts, but they do contribute to making water hard, which could have a negative impact on your home.
Reverse osmosis systems are much more thorough when it comes to removing contaminants, because that’s their main intended purpose. The process is so effective that pretty much all contaminants get taken out of the water. This also includes minerals. However, if your water is too hard, it’s recommended to use a softener before your reverse osmosis system, as otherwise you risk shortening the lifespan of the reverse osmosis membrane.
Difference #4: Installation Location
A water softener is typically installed at the point of entry, meaning that it filters water throughout your entire household, or at least major sections of it. A reverse osmosis water filter in comparison, is usually installed at a point of use.
Difference #5: Wastewater
One major disadvantage to reverse osmosis is that it tends to waste a lot of water. If you are using a basic system without any additional features, you may end up wasting as much as 3-5 gallons of water for each gallon you purify.
That being said, salt-based water softener do waste some water as well – during their regeneration cycles.
Difference #6: System Design
By first looking at a reverse osmosis system and then looking at a water softener, you can immediately tell the difference.
- Under sink RO systems have filter housings with filter cartridges, a storage tank, a dedicated faucet, a drain saddle, and lots of tubing.
- Water softeners consist of 1 large resin tank with a head valve on top and a slightly smaller brine tank.
Difference #7: Maintenance
To use a water softener, you need to regularly refill the brine tank with salt. The softening resin needs to be regenerated from time to time as well, but this is typically automated. And of course, you need to occasionally clean the brine tank and the other components of the system.
With a reverse osmosis system, you will need to replace the different filter stages at least once a year and clean the system. You might also have to pressurize the tank.
Benefits: Why Get a Water Softener?
You should use a water softener if your water is particularly hard. While this might not impact your health in any noticeable way, it will definitely have an effect on your plumbing system and water-using appliances. With hard water, scale will build upon them much faster and they will require more frequent maintenance and repairs.
Soft water also doesn’t leave spots or stains on glassware, sinks, and other surfaces, which makes cleaning a whole lot easier.
Further Reading:
Benefits: Why Get a Reverse Osmosis System?
Reverse osmosis systems are useful when your water is heavily contaminated. This is the most thorough method for filtering water available on the consumer market. No matter what kinds of contaminants you’re dealing with, reverse osmosis will very likely be a good solution to the problem and provide you with safe water for consumption.
Do I Need a Water Softener or a Reverse Osmosis System?
The bottom line is, if your water is hard, you should get a water softener. If it’s contaminated, you should get a reverse osmosis system. You might also be dealing with both problems simultaneously, in which case it’s perfectly reasonable to use both systems in combination.
Using Both: Why RO and Water Softening Work Great Together
In fact, this is a very common approach. Hard water can decrease the lifespan of a reverse osmosis system. Using a water softener is highly recommended if you want to use a reverse osmosis system with very hard water.
A Softener Softens Water, an RO Removes Contamination
So if your water is both hard and contaminated, you’ll probably want to use both solutions. The softener will remove all minerals, while the reverse osmosis system will remove everything else, including the extra sodium that was introduced into the water by the softener.
A Water Softener Protects an RO System from Fouling
If you use a reverse osmosis system with very hard water, you might end up clogging the membrane much faster than you normally would. That’s because all those minerals will start accumulating on the membrane, leading to fouling. Using a water softener before water enters the RO system is a great way to improve its lifespan.
Reverse Osmosis Removes Softening Salt
One minor downside to water softeners is that they add extra sodium to your water. This might not be ideal if you want to use that water for specific purposes such as watering your plants. By using reverse osmosis, you will get rid of all of that extra sodium, bringing your water back to normal levels.
If you have any questions about reverse osmosis vs water softener please don’t hesitate to leave a comment below!
About the Author Alexandra Uta
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