What Does a Water Softener Do?

Updated on:
October 23, 2023

The minerals in hard water can affect your property, your budget, and even your body. Water softeners mitigate these effects by producing mineral-free water that protects your household appliances and improves the appearance of your hair, skin, and clothing.

But what does a water softener do? This article covers the ins and outs of water softeners and how to use them effectively.

Read on to learn more.

Why Should You Want Soft Water?

To determine the role a water softener could have in your household, you need to understand what hard water is and the damaging effects it can have on anything from your water heater to your jeans.

Hard water is defined as water that includes calcium and magnesium ions, as well as iron, aluminum, and manganese in some locations. This can include ferrous iron, which, when oxidized to ferric iron, leaves a reddish brown stain on fabrics and enameled surfaces.

According to general water hardness classification guidelines, water that has calcium carbonate concentrations of 0–60 mg/L (milligrams per liter) is regarded as soft; 61–120 mg/L as moderately hard; 121–180 mg/L as hard; and if it’s more than 180 mg/L, it’s classified as extremely hard.

Here are some of the most typical problems caused by hard water in the home:

  • Hard water causes crusty deposits or soap scum to form on faucets, shower walls, water heaters, dishwashers, and coffeemakers. 
  • Lime scale accumulation gives an unpleasant taste to food and drinks.
  • Scale buildup reduces the efficiency of your water-using appliances, which in turn causes wasted water, premature breakdowns, and repetitive maintenance costs.
  • If you have hard water, you will notice that your fabrics are stiff and harsh after washing, or that the colors are fading.
  • Soaps and detergents react badly with hard water. Instead of producing a dense and frothy lather, it produces a curdled mess.
  • Since it strips natural oils from your skin, hard water can give you scaly, dry skin and brittle, dull hair.

All these problems can be fixed with a water softener. With softened water your appliances will last longer and your dishes will shine. You’ll also enjoy softer skin and cleaner clothes.

So, What Is a Water Softener?

A whole-house water softener is a filtration system that will remove calcium magnesium from your drinking water, as well as removing other hardness-causing minerals. 

It does this using an ion-exchange process in which magnesium and calcium ions are trapped by plastic resin beads—most commonly made of polystyrene gel—within the softener and then traded for sodium or potassium ions. Calcium and magnesium are flushed out of the resin beads using a very concentrated salt or potassium chloride solution. This final chloride solution is eventually flushed down the drain.

The components of a water softener

To understand how a water softener works, it helps to know all of its functioning parts. A water softener is made up of the following components:

The mineral tank

The mineral tank is the tall, thin tank where the water softening process takes place. It is stuffed with numerous porous polystyrene resin beads. As water flows through this tank, the negatively charged resin beads attract positively charged calcium and magnesium particles in the water and hold them in place. With these hardness minerals now trapped by the resin beads, the water that continues to flow is now soft. Ultimately, however, the beads become mineral-saturated and must be cleaned.

The brine tank

The second section of a water softener, the brine tank, is equally important to the operation. The brine tank of a water softener is separate from the mineral tank and contains a highly concentrated, positively charged sodium chloride solution. The salt forms a brine solution at the tank’s bottom, which allows the resin beads to regenerate by flushing out the hardness minerals they have collected.

As more water flows through the resin beads, they eventually become incapable of holding any more minerals. When this occurs, the brine solution enters the mineral tank and washes the resin beads clean of any hard minerals. This regeneration process is explained in more detail below.

Since water softeners require salt to regenerate, it is important to replenish the salt in your water softener according to the manufacturer’s instructions if you want to keep it working at its best.

However, salt may also harm the microorganisms in septic systems that are required for waste decomposition. As a result, sodium brine has been prohibited or restricted in some states and municipalities, including California.

Potassium might be used as an alternative for salt. Potassium is regarded as more environmentally friendly than salt, and it has no negative effects on your health, watersheds, or the operation of sewage systems, but it is somewhat more costly.

The control valve

The control valve has a meter that measures the amount of water entering the mineral tank. As hard water starts flowing through the mineral tank, the sodium ions on the resin beads are exchanged for hardness ions.

This repeated operation eventually diminishes the resin’s ability to effectively soften water. Before the beads become too mineral-laden to keep extracting calcium and magnesium ions, the control valve initiates a regeneration cycle. 

This action is preprogrammed into the onboard microprocessor of the control valve based on the following factors:

  • The size of your house
  • How many people live in your home
  • The volume of water your household consumes
  • The level of hardness in your water


A water-softener system needs resin so that the ion-exchange process can take place.

The mineral tank of a water softener has a “bed” of small, spherical resin beads. Resin beads are made of thin strands of polystyrene woven around one another like a rubber-band ball. These resin beads possess a negative charge that attracts positively charged ions. Before being packed into the water softener resin bed, the resin beads are coated with positively charged sodium ions so that they can fulfill their role in the water-softening process.

The calcium and magnesium ions found in hard water are naturally positively charged. When water travels through the water softener tank and resin bed, the hardness ions displace the sodium ions from the resin beads and bind themselves to the resin. Finally, sodium ions are discharged into the water.

Once all of the resin beads are covered with hardness ions, the water softener needs to get rid of the calcium and magnesium so it can keep collecting more. This is when regeneration takes place.

What Is Water Softener Regeneration?

Regeneration is the most technical aspect of a water softener. Once the resin has trapped all the hardness minerals it can handle, the system must be flushed with a salt water solution.

The regeneration process involves flushing the water softener for 10 minutes with pre-loaded salt pellets. Each cylinder in the system is cleaned one at a time to ensure that softened water is continuously delivered to your home. There are five cycles in the regeneration process. Let’s take a closer look at each one:

1. Filling the brine tank

Initially, water is routed into the brine tank, where it fills to just below the salt level. This water is needed to make brine, a smooth mixture of dissolved salt and water. It’s critical to keep your brine tank stocked with enough salt to produce brine at all times; otherwise, the system will just replace the resin with water.

2. Backwash cycle

The brine tank must be flushed before the resin beads are replenished, a process known as backwashing. The resin bed collects debris, grime, sediments, and fractured beads, all of which must be discarded to keep the water-softening system running well.

Water is routed to the bottom of the resin tank. It is then directed upward through the resin beads, where impurities and suspended particles are washed away.

After that, water exits the resin tank through the control valve, carrying any minerals and debris with it. This polluted water is washed down the drain after exiting the tank.

This stage of regeneration typically takes 10 to 15 minutes and operates at a flow rate of 4 to 8 GPM (gallons per minute). It is critical that the flow rate is not too high here, since this might result in resin loss. This cycle increases the space available to the water-softener resin by up to 50%, preparing it for the next cycle.

3. Brine-draw cycle

The next step of the regeneration cycle involves drawing brine from a brine tank into the resin bed. The sodium ions are traded for the hardness minerals in the resin bed when the brine solution comes into contact with them, a process known as reverse ion exchange.

For the brine draw procedure to work, a flow rate of .05 to 1 GPM is needed. Brine flow direction can be either upward or downward, depending on the water softener brand or model. Some say that upflow is the more efficient cycle, but it makes little difference either way.

This process lasts around 30 minutes. Afterwards, the resin tank will have been completely regenerated with sodium instead of the hard-water minerals. The water-softener system is now ready for soft water treatment.

4. Brine-rinse cycle

When the brine draw cycle is done, water flows into the resin tank to rinse the resin. Once more, this is a fairly slow process with a flow rate of about 0.5 to 1.0 GPM, which ensures that the reverse ion-exchange process is efficient. Any brine that is still on the resin bed is taken off and washed down a drain. From start to finish, this cycle takes around 20 minutes.

5. Fast-rinse cycle

During the fast-rinse cycle, water moves quickly through the resin bed, usually from the top to the bottom. This will get rid of any hard-water minerals and brine still in the water.

The resin bed is then packed down in readiness for the water-softening process. This is the longest cycle, and it can take up to 50 minutes to complete. This last cycle needs a flow rate of 1.5 to 2 GPM to complete.

The frequency of water-softener regeneration cycles depends on the type and model of the system. In general, conventional units regenerate every 7–10 days, whereas high-efficiency water softeners regenerate every 2–3 days.

How to Use Your Water Softener Efficiently

After your water softener is installed, some basic calibration is necessary before use, as the water-softener control valve will be preprogrammed by the manufacturer and must be modified to your household’s specific needs.

First, you need to adjust the water hardness on your water-softener control valve to match the hardness of your water source. For every part per million (PPM) of dissolved ferrous iron or manganese, increase the hardness setting by 5 grains.

Second, you need to program your control valve’s regeneration timer. When adjusting the timer, it’s okay to estimate. The most basic setting is that a one-person household requires 75 gallons of water daily. However, some manufacturers seek to be more scientific and adjust this number for their systems’ efficiency. A common setting is every six days. If opting for this preset adjustment, the water softener would renew every six days, regardless of how much water was consumed in the household.

Finally, if for whatever reason your water softener fails to regenerate, most manufacturers include an override so that the softener regenerates automatically after 14 days to preserve the system’s efficiency. The override period can be set between 1 and 28 days.

After making these adjustments, the water softener will operate automatically. No additional adjustments are necessary. All you have to do is add softening salt to the brine tank, then relax and enjoy!

What Type of Salt Is Used in a Water Softener?

Sodium chloride and potassium chloride are the most common softening agents used in water softeners.

However, some of the softening salt pellets you can buy in supermarkets have a lot of impurities in them that don’t dissolve in water. This insoluble matter can build up in the softener’s reservoir or make it stop working. If you see any signs of buildup, you’ll have to clean the brine tank more often. So, when you go shopping for softening salt, look for a label on the bag of salt pellets that says “high-purity salts.”

Sodium chloride

This is the most common type of water softening agent used today. Below is a breakdown of the different options of sodium chloride available on the market:

Solar salt pellets

Solar salt pellets are often supplied as crystals or pellets and are produced by evaporating sea water. Solar salt is more soluble than rock salt, although it may not be as effective as evaporated salt in extremely hard water. Many brands of solar salt are 99.6% pure salt.

Rock salt

Rock salt resembles pebbles or tiny rocks. Although this kind of salt is more affordable, I do not advocate using it since it includes a high concentration of calcium sulfate, which prevents it from dissolving in water and might cause maintenance issues.

Block salt

Block salt has a high concentration of calcium sulfate and is less pure than water-softening salts such as evaporated salt and solar salt. It is less soluble, which leads to accumulation and necessitates more regular maintenance.

Evaporated salt pellets

The purest of the aforementioned salts, evaporated salt pellets are also often the most expensive variety of water-softener salts on the market. The better the quality of your salt, the less water-insoluble matter there will be, reducing the likelihood of “bridging,” “mushing,” or salt accumulation at the tank’s bottom that will need to be cleaned frequently.

Potassium chloride

Potassium chloride can be used in place of salt (sodium chloride) to replenish the softening resin in the brine tank. It is 99.9% sodium free and a suitable choice for people wishing to limit their salt consumption.

Generally, potassium chloride pellets are more costly and difficult to locate than salt pellets. If switching from salt to potassium chloride pellets, the salt-dosage program settings on the valve may need to be increased by 10% to guarantee adequate regeneration of the resin.

Final Thoughts

Installing a water softening system in your home is one of the best ways to safeguard the well-being of your family. Not only will they have better skin and hair, but their clothes will also be brighter, their food will be tastier, and your home’s appliances will work efficiently. 

Instead of buying expensive specialized soaps and lotions to counteract the effects of hard water, a water softener can solve the problem right away. Read my review of the best whole-house water softeners to find out which brand is best for your home.

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Someone told me not to use softened water to mist my carnivorousness plants. I was at a botanical garden and the person in the greenhouse mentioned it. Why is that? Is it true? I have a water softener.

James Layton

Janine, Tropical plants like orchids and carnivorous like to be misted (but over-misted!). Hard water will leave a mineral residue on the plants and in the root area. But what about softened water? A water softener takes out calcium and magnesium (in exchange for sodium) but leaves all the other minerals, like sulfate, bicarbonate, chloride, etc. Misting with softened water could still leave a mineral residue on the plants. I don’t believe you need to stress out about how hard your water is or if you occasionally mist with softened water. Many hobby growers use distilled or reverse osmosis water water misting all of their plants. It is a “luxury” that works at home but commercial growers can’t afford this level of water purification. I water and mist my houseplants with RO water to minimize salt and mineral build-up. This link takes you to the American Orchid Society web site. I like it because it is a “no-hype” informational site. Browse the site and you’ll even find species-specific care sheets that make it easy to learn how to care for your orchids. American Orchid Society