How Does A Water Softener Work?

Has hard water been getting on your nerves? It's time to learn how water softener's work.

If you live in a hard water area, have you considered softening your water? Maybe you’re wondering what a water softener even does.

We dare say you aren’t alone. Over 80 percent of homes in the USA on municipal supply have hard water (1). It’s not just piped water either; even well water supplies to homes are affected (2).

Installing a water softener can help deal with the issues hard water poses for a household. Let’s look at how hard water can affect you, what a water softener can do, and how they work.

What Are the Effects of Hard Water?

We all know water isn’t hard, per se; it’s a liquid after all. What defines hardness is the quantity of minerals that are dissolved in the water — the main culprits being magnesium and calcium. This doesn’t mean your water isn’t safe to drink; in fact, the extra calcium and magnesium are great for your health.

At the very worst hard water is a little annoying, and can cause damage if unchecked. Some of the effects of hard water include (3):

  • White marks: White cloudy marks and stains on dishes, sinks, shower enclosures, glassware, and silverware.
  • Faded clothes: Laundry that comes out of the machine looking grey and dingy, and feels stiff to the touch.
  • Overconsumption: Increased use of soap, shampoo, laundry detergents, and fabric softeners.
  • Buildup: Scale buildup in kettles, irons, coffee makers, appliances, bathtubs, faucets, toilets, and sinks.
  • Home appliance damage: Damage to plumbing systems, boilers, washing machines, dishwashers, showerheads, and water heaters due to scale buildup.

Ultimately, hard water can cost you money. You may end up buying more cleaning products for your home and your hygiene. But even worse, the scale buildup in your plumbing system and household appliances can restrict the amount of water getting through. This means they have to work harder, expending more energy, and increasing your bills.

Hard water is a widespread problem in the US. Fortunately, installing a water softener could be an investment that will save you money in the long run.

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What Is a Water Softener?

Water softeners are systems designed to accommodate the demand for water in your whole home. They’re often installed in a garage, utility room, basement or wherever your water supply enters your home.

The different types of water softeners we’ll cover include:

  • Ion exchange softeners.
  • Demand initiated regeneration systems.
  • Template Assisted Crystallization (TAC) or Nucleation Assisted Crystallization (NAC).
  • Chelation systems.
  • Magnetic or electronic water softeners.
  • Reverse osmosis systems.
  • Showerhead filters.

How Does a Water Softener Work?

Ion Exchange Softener

Ion exchange softeners are the most common types of water softeners. They contain two separate tanks; each plays different, yet integral, roles in the softening process.

The Softener Tank

  1. Water enters the tank: Your water supply enters the top of the softener tank and filters down over resin beads, which are coated in sodium. The simple science here is that negative and positive ions attract each other (4). So, the resin beads with sodium have a negative charge, and the minerals in the water, like calcium and magnesium, have a positive charge.
  2. Ion exchange: This is where the “ion exchange” happens, and the minerals in the water adhere to the resin in the tank. The result is the magnesium and calcium stick to the resin, and the sodium is released. This exchange helps keep the status quo of electrical charge on the resin.
  3. Soft water: The result is softened water flowing out to the faucets and appliances in your home.
  4. Cleaning with brine: Eventually, the beads in the softener tank will reach capacity and won’t be able to hold onto or attract any more of those pesky minerals. When this happens, the softener tank needs to be cleaned or regenerated.

The Brine Tank

Now it’s time for the salt tank to go to work.

  1. Salt released: The digital control can be preset to initiate the start of the cleansing process. When this happens, salt is released into the water and passes from the brine tank into the softener tank.
  2. More ion exchange: It’s back to ion exchange again. This time, the exchange reverses, and the salt sticks to the resin, releasing the minerals collected back into the water.
  3. Flush: This mineral-rich water is then flushed out through the drainage hose.
  4. Cycle repeats: Once this “rinse cycle” is complete, your water softener goes back to work — supplying your home with soft water.

We also mentioned potassium chloride earlier; this can be used as an alternative to salt in the brine tank. The principles are the same, but it reduces the amount of sodium passing into your softened water. This could be a preferred option for those who need to control the sodium in their diet; however, it’s a more expensive option.

Take Note

The brine tank will need to be refilled with either salt or potassium chloride pellets from time to time. The frequency of this will depend on your water consumption (5).

Replacement salt is readily available, like these salt pellets or potassium chloride pellets from Morton.

Demand Initiated Regeneration System

This is a more sophisticated system that tracks your water usage and flushes the system to regenerate it only when it’s needed. This can be more economical as it will save money on replacing salt used from flushing unnecessarily. It also means that you won’t have hard water if your consumption is more than usual and your preset rinse hasn’t kicked in (6).

Template Assisted Crystallization (TAC) or Nucleation Assisted Crystallization (NAC)

If you’re looking for a healthier option to using salt in a water softener, this one could fit the bill.


Sometimes called water descalers or water conditioners, these systems don’t remove minerals from your water. This could make it difficult to ascertain whether your water is actually softer.

What these systems do is convert the minerals in your water to crystals that are unable to adhere to your plumbing pipes or appliances.

  1. Polystyrene: The water passes over polystyrene beads, which act as a catalyst for the crystals to form.
  2. Crystal growth: The crystals then grow on the beads.
  3. Crystals removed: When the crystals get larger, they pass into the water system and get flushed away.

The minerals that cause water hardness are still in your water, but they can’t stick to anything, so your water no longer has the properties of hard water.

The benefits of this type of system are that it doesn’t require energy to work and there’s no regeneration process. This, ultimately, saves money on lower water and energy bills.

Chelation Systems

Chelation systems are water conditioners that require no salt. This time, the agent that deals with the water hardness is one such as nitriloacetic acid, or another form of citric or oxoic acid. These chelating agents adhere to minerals in the water, suspending them there — and preventing them from building up on pipes and appliances (7).

Like a TAC system, a chelation system is a descaler as opposed to a water softener. They tend to be found more in commercial settings.

Magnetic or Electronic Water Softener

Magnetic or electronic softeners (or descalers) are some of the newer kids on the block. They require a power supply and are fitted to a pipe in your home where the water supply enters it.

When the water flows over the device, the generated magnetic fields alter the electromagnetic properties of minerals in your water. In doing so, the calcium and magnesium carbonates aren’t attracted to each other. Nor do they stick to your plumbing, keeping limescale build-up at bay.

The effectiveness of these systems could be questionable as they don’t remove hardness the way an ion exchange system does. Then again, they’re intended to prevent scale from clogging your system as opposed to softening your water.

Reverse Osmosis System

A reverse osmosis system has lots of fine filters that remove solid contaminants from your water. This includes calcium and magnesium, as well as other organic and inorganic materials (8).

These systems attach to a water source within your home, such as the kitchen or bathroom faucet. They don’t provide whole-home filtration.

Replace Minerals

It’s worth noting that the nature of these systems means all minerals good for your health are removed. To ensure your body gets the minerals it requires, eat a healthy diet.
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Showerhead Filter

As the name suggests, these are filters that attach to your shower head. They are an easy-to-install option for removing minerals via a fine filter before water leaves your shower head. They don’t soften your water per se but do remove contaminants and minerals before they get to your body.

The result is less soap scum and less clogging of the water holes in your showerhead from scale build-up.

Figuring it Out

Hard water can, at best, be an inconvenience and, at worst, clog up your plumbing and appliances. This can ultimately cost you more money than it would to install a water softener.

Knowing how water softeners work should help you see the benefits you can reap from having soft water in your home. These include lower energy bills, fewer cleaning products for you and your home, softer, cleaner clothes, and fewer stains and marks.

We know that a softener might not be suitable for everyone. But, at least you can now make an informed decision as to whether this is the solution you’ve been looking for.

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About the Author

Peter Gray

Peter has been a homeowner for 35+ years and has always done his own repair and improvement tasks. As a retired plumber, Peter now spends his time teaching others how they can fix leaks, replace faucets, and make home improvements on a budget.