What is water softener salt?

Last updated on: April 1, 2024.

Hard water contains high hardness levels, causing minerals such as calcium and magnesium. Regular use of hard water can be tough on your household appliances, the pipes and plumbing system, and even your clothes.

Hard water leaves you feeling sticky with soap even after a wash, and the kitchenware shows white spots. It is because hard water takes longer to lather, making you use more soap, and it is harder to rinse completely. The same is true when you shampoo your hair and your hair feels dry even after a wash and loses the shine. Over time, hard water causes limescale buildup on your appliances, reducing their lifespan. For all these reasons, we need a water softener. 

What is a water softener?

Water softening systems work through an ion exchange process with the help of a resin tank. The resin beads trap the hard minerals and swap them for sodium during regeneration. Resin beads are polystyrene wrapped around in a criss-cross fashion with some Divinylbenzene that glues the beads together. The hard minerals have positive ions, and sodium has negative ions.

When the water flows over the salt-based resin bed, the positive ions get attracted to the negative ions and are captured in the resin bed. After a while, the resin bed becomes saturated with the hard minerals, losing sodium effectiveness, and the system goes through a regeneration process.

Salt is needed for the regeneration process as it is strong enough to draw the hard minerals soaked into the resin beads to clean the resin bed and prepare it to begin the water softening process again. It is a continuous cycle performed by water softeners. 

Why do softeners need salt?

There are two reasons why most water softeners are salt-based. Salt is non-toxic and inexpensive. It also allows ion exchange without affecting the taste of the softened water. As to why salt is needed in water softeners, it is because it helps clean the resin beads. 

We add salt pellets to the resin tank to pull out the hard minerals to flush them down the drain. This makes salt essential to water softeners. It is used to remove the hardness and to stimulate the ion exchange.

The amount of salt needed to soften water in your home depends on the number of people in the household. It also depends on the hardness levels in the water.

For instance, a couple will need around 80 pounds of salt in their water softeners every two months. If you are a family of four members, you may need to use an additional 40 pounds of salt. If the water’s hardness level is high, your water softener may require more salt. You will get the most benefits by using evaporated salt pellets.

What is water softener salt made of?

The salt in water softeners is made of sodium chloride (NaCl). It may also be made of potassium chloride (KCl). The salts used in a water softener can come in blocks, crystals, cubes, rock, and pellets. There are also solar and evaporated salt pellets.

Salt crystals

Evaporation causes the formation of salt crystals when a mixture of salt, water, and brine is exposed to wind. It contains around 99.6% of sodium chloride and is more suitable for smaller households with less water usage. You can also use it in a two-part water softening system. 

Solar sea salt

As the name suggests, solar sea salt is due to the evaporation of seawater. Solar salt is available in a pure form with 99.5% of salt, with a minimum of other materials, if any. It is also more soluble than other types of salt. 

Rock salt

Rock salt is irregularly shaped and is cheaper than other types of salt. But, it is not as pure because it has some amount of calcium sulfate. It also doesn’t dissolve in water as easily as the pure types of salt do. Therefore, it leaves a residue in the water softener’s brine tank requiring frequent cleaning. 

Evaporated salt pellets

You get evaporated salt pellets by refining the salt crystals into sodium chloride. These salt pellets contain 100% pure salt making them the best type of salt to use in water softeners. They dissolve easily and don’t leave any residue. While the evaporated salt pellets may be a tad more expensive than other types of salt, they still work more efficiently. 

Potassium chloride

Potassium chloride can work well for those who do not want more sodium added to their water or are on a low-salt diet. Potassium softens the water, too, and provides softened water with no saltiness to the taste.

While understanding the types of available salt for water softeners will help to know the purity levels of the salt.


In some cases, there is a certain amount of material in addition to salt. Purity is measured by considering these extra materials in salt. If the salt is pure, it will have less insoluble material like particulates from earth or rocks. It is a given that pure salt will last longer and will not leave any residue in the water softener’s brine tank. Pure salt also reduces the risk from salt bridges and can ensure that the pipes and the water softener system do not get clogged. 

Another thing to consider is the maintenance required for the water softener. The type of salt you use will directly impact the system. Impurities in the salt, such as rocks or earth, will leave deposits in the unit. These deposits can build up over time, and you must flush out the deposits in the water softener. With the continued use of the water softener, the deposits that accumulate and need to be flushed out will wear out the machine faster.

Moreover, impure salt increases the chances of salt bridges. A salt bridge occurs when salt hardens and forms into clusters or a rigid crust in the brine tank. As the crust builds up, salt is prevented from getting into the water softener. Salt bridges are not always noticeable immediately as they form below the top layer of the salt in the tank.

Which salt is best for water softeners?

diamond crystals

While there may be different types of salt in the market, the Diamond Crystal 804017 Solar Natural salt is the best for water softeners. 

Diamond crystal salt is known for its purity of up to 99%. It uses Cargill extra coarse solar salt. This salt helps remove corrosion and ensures softened water for all household purposes. These salt pellets dissolve easily, leaving no residue in the tank. As soon as you add the Diamond crystal salt pellets, the conversion begins, and the quality of the water improves almost immediately.

There are many pros to investing in Diamond crystal solar, natural salt. It offers 99.8%, removes corrosion from the water, increases the lifespan of all appliances, and makes the water softer, odorless, and tasteless. The only negative factor is the cost, as it is more expensive than other water softener salts.

What is the difference between table salt and water softener salt?

While water softener salt comes in larger crystals or pellets and is not meant for eating, it has been formulated to remove minerals from hard water. Table salt is fine-grained and iodized for human consumption.

What happens if the water softener runs out of salt?

Now that we know about salt-based water softeners, it will help us understand what happens to the water softener when it runs out of salt. You will see a few clear signs that indicate that your unit needs salt.

The soap will not lather up, and you will find yourself using a lot more of it to get a lather. It will also leave a sticky film on your skin. The glassware and kitchenware will start showing white spots, and the hard minerals will start building up in your pipes. Your water heating system will lose its efficiency. The white crust will form on the faucets and showerheads and obstruct the free flow of water. If you use a non-electronic water softener, the tank can also overflow when it runs out of salt. 

You can lift the cover of the brine tank and check to see if the salt is dry and the tank is less than half full. You will know if it is time to add more salt. 

New water softeners come with an indicator to show if the unit is running low on salt. They use a sensor that alerts you to the level of salt in the water softener. 

How often should you add salt to water softener?

Ideally, you should add salt to the water softener twice a month. When you check the brine tank and find that the salt has submerged below the water level, you will need to add salt and top up the tank. The amount of salt you add and the frequency will depend on how hard the water is in your home and how much water is getting used.

Frequently Asked Questions:

1. How much does water softener salt cost?

Salt for water softeners can cost anywhere between $5 and $25 for a 40-pound bag. The rate depends on the purity of the salt and also from where you are buying the salt.   

2. Is water softener salt the same as rock salt?

Rock salt refers to unprocessed sodium chloride that is taken directly from the ground. It is also known as sidewalk salt. Using rock salt in a water softener is not a good idea as the rock salt contains insoluble materials that can clog up the resin bed. You may find yourself cleaning the water softener far more frequently if you use rock salt. 

3. How long does salt last in a water softener?

The salt you add to the brine tank gives the resin beads their sodium ions. The amount of salt the resin beads need will depend on the water hardness and water usage. Typically, the salt can last around two months before needing more.

4. Where can you get water softener salt?

You can get water softener salt from any of the water softener equipment suppliers. You can find it online and at the local hardware stores. It is quite a common product as there is increasing use of water softeners. 

5. Is there a difference between cube and pellet-type salt?

Water softener cubes and pellets are made from sodium chloride. The only difference lies in the way they are produced. The large-sized pellets and cubes have less chance of causing salt bridges, unlike the smaller crystals. In short, pellets and cubes can be used interchangeably.

6. Is the water softener salt in any way harmful to animals?

Obviously, water softener salt is not advisable for human or animal consumption. Also, the size of the salt may be too big for smaller animals. Your animals will be better off without water softener salt in their food or water.

7. How many bags of salt do you need for a water softener?

The amount of salt needed for a water softener depends on the hardness levels in your water. For instance, hardness levels over 10 grains per gallon will need more salt. You can safely assume that you will need at least twelve bags of salt per year, with each bag holding 40 pounds of salt.

8. Which salt is best for water softener?

Due to their high effectiveness and purity in water softening, evaporated salt pellets are considered the best for water softeners.


With the many types of water softener salt in the market, it can be a little difficult to choose the right one. You will need to keep a few aspects in mind, such as the quality of salt, the amount of salt you are likely to need, the hardness levels in your water, and your budget. While the best type of salt may be more expensive, it may also have the highest purity level, as in the case of Diamond Crystal solar, natural salt. Therefore, it makes sense to invest in the best as it will prove it’s worth many times over. 

About The Author

Our Web Producer

Judith— a passionate water treatment specialist — is a waste water management enthusiast, clean drinking water advocate, and someone with deep personal experience and knowledge about various water equipments. Her work was mentioned in countless notable water associations. Previously she was an editor at Water Alliance.