What Kind of Salt Should You Use in Your Water Softener? (2024)

We’ve been reviewing and recommending water treatment systems for over a decade, and have racked countless hours testing salt-based water softeners.

Based on our experience as water treatment professionals, we’ve outlined the different types of salt for water softeners, and what makes them unique from one another, in this article.

📰 The 6 Different Types of Water Softener Salt

Here are the 6 different types of salt that can be used in the water softening process.

Evaporated Salt

Evaporated salt is the highest-quality and highest-purity salt, and is up to 100% pure. This type of salt is made by an evaporation process involving steam and water.

Best For:

The best time to use evaporated salt is if your water is very hard. You should also use it if you prefer to spend slightly more money upfront on high-purity salt that will last longer and minimize your water softener brine tank cleaning commitments.

Evaporated Salt Advantages

• Evaporated salt contains virtually no impurities, so they’re clean and produce minimal buildup in your brine tank.
• This type of salt is highly effective in regenerating a water softener’s ion exchange resin, and is one of the most efficient at removing hardness minerals like calcium and magnesium from water.

Evaporated Salt Disadvantages

• Because you get up to 100% salt in each bag of evaporated salt pellets, it’s usually more expensive than other water softener salts.
• The process of producing evaporated salt is energy-intensive, so it’s not the most environmentally friendly salt for your water softener system.

Rock Salt

Rock salt, which gets its name from its appearance (it looks like small pebbles or rocks), is mined from underground salt deposits. It’s more affordable than other water softener salts, but there’s a reason for that – it usually has a high calcium sulfate content.

Best For:

Based on our own experience offering professional recommendations for the right water softener salt, rock salt is never the “best” option. However, it’s at least acceptable if the manufacturer says it’s suitable to use in your water softening system.

Rock Salt Advantages

• Rock salt is more affordable compared to other types of salt used in water softeners, making it a cost-effective option.
• It’s also widely available and accessible, so it’s convenient and easy to buy from multiple locations if you unexpectedly run out of softener salt.

Rock Salt Disadvantages

• Rock salt is typically higher in impurities, which can contribute to the buildup of sediment in the brine tank and potentially the quality of your softened water.
• Because of this, it has a higher insolubility rate compared to other salt types, which means it’s more prone to salt bridging or mushing in the brine tank, so you’ll need to clean your softener more regularly.

Solar Salt

Solar salt is available in pellet or crystal form, and is formed by pumping seawater into large, shallow ponds, where the sun and wind cause the water to evaporate, leaving concentrated salt.

Best For:

Solar salt is effective for softening moderately hard water. However, if your water has high levels of hardness, we don’t recommend solar salt because it tends to have lower purity levels compared to other types of salt, so it’s not as efficient.

Solar Salt Advantages

• Solar salt is often more affordable compared to evaporated salt, so it’s more of a cost-effective option for using in your water softening system.
• It’s made using renewable sources of energy, so it’s more environmentally friendly than evaporated salt.

Solar Salt Disadvantages

• Although it’s purer than rock salt, solar sea salt may still contain impurities and other minerals from the seawater, which can lead to sediment buildup in the brine tank. It’s around 99.6% pure, versus evaporated salt’s 99.9-100% purity.
• It’s also not recommended for very hard water because of its lower purity, which means it isn’t as effective as evaporated salt. The USGS classes “hard water” as having a calcium carbonate concentration of 121mg/L or higher.

Block Salt

Block salt is a low-cost softening salt that can be used in a brine tank with a raised water level. It’s made by purifying and compacting high-purity salt, usually sodium chloride, into dense, solid blocks.

Best For:

Block salt is only best for certain types of water softeners that have brine tanks that accommodate the shape the the blocks. Most manufacturers advise against using block salt in their water softening systems.

Block Salt Advantages

• Block salt has a high purity of around 99.8%, so it’s an efficient type of salt to use that’s unlikely to develop into a salt bridge.
• Block salt is convenient to handle, especially when we compare it to traditional bags of salt pellets or crystals. The compact, solid blocks are easy to load into water softener units.

Block Salt Disadvantages

• Only certain water softeners can be used with block salt, so it’s not an option for everyone.
• It’s important to completely submerge the salt blocks to prevent bridging at the top of the tank.

Specialized Water Softener Salts

There are a few types of specialized water softener salts that you can buy for specific purposes. These include:

• Water softener pellets with added resin cleaning additives.
• Water softener salt that’s specially formulated for addressing low concentrations of dissolved ferrous iron.

Best For:

Specialized softener salts are best for when you want to tackle a specific water quality or softening system issue alongside hard water.

Specialized Softener Salt Advantages

• Specialized softener salt provides two benefits in one: water softening and resin cleaning/iron removal.
• It’s often more economical to use these salts rather than to buy a separate treatment product. This is especially the case if you want to target low levels of iron in your water without investing in an entirely separate filtration system.

Specialized Softener Salt Disadvantages

• Only a few brands sell specialized salt for water softener systems, so you’re not guaranteed to find the best quality product.
• These salts are usually more expensive due to their additional abilities.

Potassium Chloride

Water softener salt does, of course, increase water’s sodium content. A 1997 study found that softened well water contained an average of 2.5x the amount of sodium compared to local municipal water – the exact amount of sodium added depends on the initial water hardness level.

The best alternative to sodium chloride is potassium chloride pellets. Potassium chloride is typically extracted from underground mines before being processed into pellets.

Best For:

Potassium chloride is best used as a sodium-free alternative for water softening. It isn’t actually a type of salt, but it can be used in place of other salt varieties in water softeners because it works exactly the same as sodium chloride during the softening process.

Potassium Chloride Advantages

• Potassium chloride is sodium-free, so it’s a great choice for people who want to actually soften their water (as opposed to using a salt-free water conditioner) without the possible side effects of sodium use.
• It’s ideal for folks who don’t want to add salt to their water or are on a health plan that requires them to follow a low-sodium diet.

Potassium Chloride Disadvantages

• Potassium chloride pellets aren’t quite as effective as sodium chloride for softening, so you’ll need to set your water hardness slightly higher on your softener to ensure all minerals are removed.
• It’s also more expensive than conventional softener salt, and less widely available.

🆚 What’s the Difference Between Water Softener Salt Crystals and Pellets?

Many types of water softener salt come in two different forms: crystals and pellets.

The main difference between salt crystals and pellets is their shape and size. Water softener salt crystals are small, individual granules with an irregular crystalline structure, and look like coarse table salt. Salt pellets are compressed into uniformly shaped pellets, which are denser and more compact.

Is it better to use crystals or pellets in a water softener? While both types of salt serve the same purpose and can be used interchangeably in water softeners, some folks prefer pellets for their uniformity, ease of handling, and reduced risk of bridging, while others go for crystals, preferring their natural, unprocessed form.

🔎 What Is Water Softener Salt Purity?

The purity of salt for water softeners is a measure of how much salt the product contains.

The higher the purity, the higher the percentage of salt. So, a salt product with 100% purity is 100% salt, while a salt product with 84% purity is only 84% salt.

If the salt isn’t completely pure, it may contain impurities like dirt and sediment (from the natural environment), and chemicals and metals (from processing).

These impurities will build up inside your water softener brine tank. That means you’ll need to clean the brine tank more frequently to prevent the impurities from blocking the salt screen and pipe leading to the resin tank. Impure water softener salts are more likely to cause clogging issues than pure water softener salts.

🧂 Can You Use Table Salt in a Water Softener?

Table salt is cheap and easy to come across, but it’s not suitable for using in a water softener.

Table salt granules are tiny, and are more susceptible to mushing – something that happens when salt collects at the bottom of the brine tank, blocking the pipe that leads to the resin tank.

It’s also likely to contain impurities and additives, meaning it’s not an efficient softening salt, and it’s likely to clog the brine tank, requiring more maintenance.

We strongly recommend sticking with types of salt that are specifically advertised for use in water softener systems.