What Is a Water Softener? (2024)

Updated on:
February 7, 2024

While water softeners don’t come up in everyday conversation, most people need a water softener system for their everyday life, including you. Your water supply could be full of dissolved minerals, which is fine—if you’re okay with buildup in your pipes and dry skin.

That’s right. There’s calcium and magnesium ions floating in your water supply, mucking things up without you ever knowing. 

Knowledge is power. The first step in figuring out if you could benefit from the water softening process is asking, “What is a water softener?”

See? Knowledge. By the time you’re done with this article, you’ll know all about water softeners, whether your house could use one, and a whole lot more.

What Does a Water Softener Do?

A water softener does exactly what it sounds like it does—it softens water. But what does “softened” water even mean? Does that mean there’s “hard” water at some point? 

Let’s start with the basics. A water softener intakes hard water and generates softened water. Hard water is the water that’s coming into your house full of calcium, magnesium, and other positive ions. The hardness of water is determined by the concentration of this mineral content. 

In other words, the more hard water minerals floating around, the harder the water. The harder the water, the stronger the water softener required to remove hardness minerals. All water softeners will remove hardness minerals, such as calcium, magnesium, and iron, but the larger, higher granulated tanks are necessary to soften higher concentrations of minerals.

To sum things up, what a water softener does is soften hard water by extracting hardness minerals. How? Magic, also known as chemistry. I’ll get into that in the next section.

How Does a Water Softener Work?

If you want to know all the intricate details about how a water softener works, I’m afraid you’ll have to do further reading. But if you want a brief overview and chemistry crash course, you’re in the right place.

The first thing you need to know is that there are a few different types of water softeners:

  • Ion exchange
  • Reverse osmosis
  • Salt-free
  • Magnetic

By far the most common kind is the ion exchange water softener, so I’ll be focusing on that. Ion exchange water softeners have a two-tank system that includes the mineral tank and brine tank. Whether you’ll have your water softener installed by the professionals or do it yourself, it’s good to know what these tanks are doing to your water supply after being installed in your plumbing system.

Mineral tank

The taller, slimmer tank of the two is the mineral tank. It may also show up as the water softener tank or simply the softener tank.

The mineral tank is home to resin beads, which are critical in the water-softening process. Here’s where we get into the chemistry portion. Whether you like chemistry or not, you’ll need to learn about it to understand water softeners.

For starters, resin beads are negatively charged. Sodium ions are positively charged. Opposites attract. Before any mineral ions enter the picture, sodium ions are resting in the pores of the resin beads.

However, when those calcium and magnesium ions in your water flow into the softener tank, they displace the sodium ions. They form a stronger bond with the resin beads than sodium ions, so they leave the hard water for the resin beads. The sodium ions get dropped into the newly softened water. As you can see, the ions are switching places on the resin beads. That’s why it’s called the ion exchange process.

To sum up, the water softener tank is connected to the home’s water supply line. When hard water flows through resin beads in the mineral tank, the calcium ions and magnesium ions are attracted to the resin beads, leaving the water. Sodium ions that were originally bonded to the resin beads get replaced by the minerals and dropped off in the water.

Brine tank

What happens when the resin beads reach maximum capacity? Can they attract any more mineral ions? Nope. Luckily, the water softener also contains a brine tank, which is full of salty water that’s perfect for resetting the resin beads.

Before you get a water softener installed, you should know that some of its maintenance includes replenishing the sodium chloride or potassium chloride supply. That just means checking that the brine tank is half filled with salt pellets, usually on a monthly basis.

Once the resin beads are full of hardness ions, it’s up to the brine tank to take care of the regeneration process. To begin regeneration, water must be added to the salt pellets to create salt water. The salt water will then pass through the mineral tank, removing positive hardness ions from the negatively charged resin beads.

The highly concentrated solution of salt is strong enough to knock off those calcium and magnesium ions the resin beads have been accumulating from your hard water. Sodium ions once again attach to the resin beads, regenerating that initial weaker positive charge that will get replaced when hard water passes through.

After the brine solution gets depleted from the regeneration cycle, the waste water passes through the drain hose. Certain plumbing systems may require the drain hose to be in a utility sink or other location, but you’ll figure that out when the water softener is installed.

Alternative Water Softeners

Not all water softeners operate with an ion exchange system, though. There are a few other kinds that don’t use plastic beads, sodium ions, and ion exchange.

Each alternative type of water softening system has its own benefits and downsides. So if you’re wondering what a water softener system is, you need to know the different water softening mechanisms.

Salt-free water softener

Once again, the water softener industry didn’t get creative with the name of this system. The salt-free water softener does NOT require salt to create soft water, unlike the ion exchange system.

Technically, according to Culligan Water, this water softening method is conditioning rather than softening your water. Rather than use salty water and an ion exchange process to purge minerals from hard water, salt-free systems chemically alter those minerals.

I won’t go into details about how the positive ions are altered. All you need to know is that through template assisted crystallization (TAC), hard minerals are turned into a “harmless crystalline form” (as explained by Pure Water Products). 

In their new harmless form, the minerals can’t form hard water deposits. That means no calcium and magnesium buildup in your pipes or on your surfaces.

Reverse osmosis water softener

The reverse osmosis water softener has a few different parts than the ion exchange system. Instead of a softener tank and brine tank, there’s a semipermeable membrane, sediment filter, and carbon filter (as stated by Fresh Water Systems).

These filters and semipermeable membranes filter out calcium and magnesium ions (i.e., hard minerals) along with dirt, dissolved contaminants, and anything else that worsens your water quality.

In this system, the membrane is the star of the show. The other filters help out before and after, but the membrane removes all organic compounds.

At the end of the day, the reverse osmosis system uses filters and membranes to execute the job of a water softener—making soft water.

Magnetic water softener

The magnetic water softener is a newer solution to reducing water hardness. According to Guardian Water Services, these water softening systems use electromagnetic coils to separate particles like magnesium and calcium ions in the water. Basically, a magnetic field is applied as water flows through your pipes, separating out hardness ions.

Recent research shows that the application of a magnetic field takes away magnesium and calcium’s ability to form “dense deposits.” 

There’s no regeneration process or brine solution required. The magnetic water softener will create soft water in an environmentally safe manner while using minimal equipment.

Water Softener Pros and Cons

You’re well on your way to becoming a water softener expert. You know what the regeneration process is, how water softening systems soften water, and what makes hard water hard.

But there’s still plenty left to learn, including the pros and cons of using a water softening system. In this case, I’ll be talking about the ion exchange system because it’s the most popular type of softener out there. (The following information is provided by the Minnesota Department of Health and Fresh Water Systems).


  • No mineral buildup in your pipes
  • Extended lifespan of appliances like washing machines, water heater, dishwasher, etc
  • Reduced soap scum on dishes and tub or tile surfaces
  • Hydrated skin and hair
  • Cleaner and brighter clothes that don’t fade as quickly


  • Corroded pipes, leading to copper and lead in drinking water
  • Negative health effects from elevated sodium in diet
  • Waste water that isn’t environmentally friendly
  • Fees from the water softener itself, installation, and maintenance

These lists will look a little different depending on what kind of water softener you purchase. While the ion exchange system elevates sodium in your diet, the magnetic water softener does not. While the ion exchange system requires biweekly or monthly maintenance, the reverse osmosis system does not.

Are There Any Health Effects From Using a Water Softener?

It’s only natural to question anything that has to do with your water supply, especially your drinking water.

As I detailed in the ion exchange process portion of this article, the resin beads of the mineral tank have sodium ions in their pores. When magnesium, calcium, and other minerals flow through the mineral tank, the sodium is displaced and released into the water supply.

While the minerals have been taken out, you’re left with water that has higher sodium levels than usual. 

According to Pennsylvania State University, using a water softener poses negative health risks for those adhering to a low sodium diet. The research shows that high levels of salt contribute to heart failure and chronic kidney disease. For someone who’s at risk for these diseases, lowering their sodium intake is critical. A traditional water softener might not be the best choice.

On the opposite end of the spectrum, using a water softener can have positive health effects by reducing strain on your kidneys. Past studies have compared hard tap water and soft water and their effects on calcium concentrations in urine. They found that soft water is better than hard water at preventing calcium stones, also known as kidney stones.

Lastly, hard water is known to increase breakage and decrease the strength of your hair due to reactions with calcium and magnesium. Water softeners remove calcium and other minerals, leading to softer and more resilient hair.

Where Can You Get a Water Softener?

If you’ve ever seen a water softener, you already know how large the tanks are. And those brine tanks and mineral tanks only get larger the harder your water is!

Luckily, there’s no shortage of water softeners. You can find them at your local hardware supply store or warehouse.

Installation is another story. While there may be chain stores or local stores that sell different brands of water softeners, the cost of installation will vary. To have the professionals bring the water softener over and install it in your current plumbing system, you could be looking at a few hundred dollars to a few thousand.

The cost is highly dependent on your region, where you purchase your water softener from, and what your current plumbing system looks like. For more detailed information on water softener installation, head over to my article on the topic.

But buying a water softener outright isn’t the only way to go about it. Depending on where you live, renting your water softener could be a great option. You’ll still have to get it installed, but renting a water softener could save you money overall while helping your pipes and softening your drinking water.

How Do You Know If You Need a Water Softener?

Now that you know what a water softener does, it’s time to figure out whether you need one.

As you know, minerals from your hard water can cause buildup in your pipes, coat your dishes, and shorten the lifespan of your heating elements. If there’s scum in your shower and you step out of it feeling a soapy film on your skin, that’s a pretty good indication that your hard water needs to be softened.

But there are more official ways to figure out if you need a water softener. You can grab a test kit from your local hardware store, send samples to a national laboratory for testing, or hire a specialist to test your water for you.

There are a few different units of measurement that are used to describe water hardness. The US Geological Survey uses a scale of mg/L (classified by amount of dissolved calcium):

  • Soft: 0–60 mg/L
  • Moderately hard: 61–120 mg/L
  • Hard: 121–180 mg/L
  • Very hard: 180+ mg/L

There’s definitely a tipping point between soft water and hard water. It makes all the difference when it comes to the longevity of your water heaters, washing machines, and other appliances.

For more information about measuring water hardness, you can head over to my ideal water hardness article. As a general rule of thumb, if you’re having problems with buildup in your pipes and scum on your surfaces, it’s time to test your water hardness. A water softener is probably in your future.

What Water Softener Is Right for You?

If you’re at a point in your hard water journey where you know you need a water softener tank, you’re also ready to figure out which water softener is right for you.

As I discussed before, water softener systems using the ion exchange process are the most common. As a self-proclaimed water softener expert who regularly writes water softener reviews, you can trust my opinion.

But water softeners aren’t a one-size-fits-all ordeal. The right water softener for you will depend on many factors:

  • Water hardness
  • Plumbing system
  • Region
  • Dietary restrictions (e.g., low sodium)

This short list is only the beginning of your water softener worries. You’ll also need to consider whether you’d like to rent or buy your system, how long of a lifespan you’re looking for, and which type of water softening system best suits your needs.


Discovering what a water softener is and whether you need one is a complicated, chemistry-oriented process. But you’ve made it!

In the last few minutes, you’ve learned about the primary goal of all water softeners (to soften water), how they work (usually the ion exchange process), alternative water softeners available (salt-free, reverse osmosis, and magnetic), and how to figure out which water softener is right for you.

You know how to identify whether your water is too hard, where to look for water softeners, and options for installation. You’re basically an expert.

So the next time you step out of your shower and notice soap scum on your tiles, you’ll know what to do.

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