How Much Salt do You Put in a Water Softener?

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Wondering how much salt to put in your water softener?

There are a few factors that affect how much salt water softeners need. We’ve shared everything you need to know in this guide.

📌 Key Takeaways:

  • Water softening systems need salt for ion exchange – removing hardness minerals and exchanging them with sodium.
  • On average, a water softener needs between 1 and 1.5 40-pound bags of salt per month.
  • Make sure the brine tank is never less than one-quarter full of salt.

🧂 Why Do Water Softeners Need Salt?

Just a quick recap in this section.

Water softeners have a separate brine tank that supplies salt, which is needed for the ion exchange process. Salt in the water softener brine tank dissolves in water, forming a brine solution.

The brine flows into the resin tank when the water softener performs a regeneration cycle. It flushes the hard minerals out of the resin beads (which have accumulated during the water softening process) and replenishes the sodium ions.

Salt is a good choice in a water softener because it’s not toxic or harmful at low levels and it doesn’t form scale.

Ion exchange process in a water softening system
Ion Exchange Process

📥 How Much Salt Does A Water Softener Need?

The average water softener needs between one and one-and-a-half 40-pound bags of salt per month.

This is assuming that the water softener has a small-to-medium capacity of around 32,000-40,000 grains and is serving a family of four.

The bigger the water softener and the more soft water required per day, the more salt a water softener will use.

📏 How Much Salt Should You Add To A Water Softener?

You should add about 40 pounds of salt to your water softener brine tank per month.

You don’t need to measure out the amount of salt to make sure you get it right. Do it by eye – when the salt level has dropped, you know you need to add more salt.

We recommend checking your salt level at least once every 3 weeks. Make sure to maintain the proper amount of salt – that means adding salt when the levels drop too low, but not exceeding the maximum recommended level in the brine tank.

Here are the three rules to remember when adding water softener salt to the brine tank:

  1. Make sure the tank is at least one-quarter full of salt, no matter what.
  2. Don’t exceed the maximum salt fill level in the tank. That’s usually 4-6 inches below the top of the tank.
  3. Make sure the salt level is always higher than the water level by a couple of inches.

Depending on the type of water softener & model you own, the rules regarding salt top-ups might be slightly different. Check your user manual for the exact instructions on how to correctly top up your brine tank.

Related: How to identify my water softener?

Adding salt to a water softener

📖 Factors Affecting Salt Top-Up Frequency

There are a few factors that affect water softener salt usage, and how often you’ll need to top up the brine tank:

Brine Tank Size

The size of the brine tank affects how much salt can be stored in the tank at once.

Most brine tanks can hold 3-6 gallons of water. The bigger the brine tank, the greater the amount of salt that can be added to the tank before the maximum fill line is reached.

Effectively, this means you should be able to go longer between salt top-ups.

📌 Keep in mind, however, that bigger brine tanks are often included in bigger systems designed for larger households.

So, even though the brine tank holds more salt, it might not have a noticeable effect on salt top-up frequency because you’re using more water than the average family.

Salt tablets in the bottom of a water softener brine tank

Salt Purity

Different types of water softener salts have different purity levels. The higher the salt purity (i.e. the higher the percentage of sodium chloride), the longer you should be able to go between topping up the salt levels.

Why? Because high-purity salt (such as evaporated salt and solar salt) is almost 100% salt, which means you’ll be filling the tank with more salt compared to using a low-purity salt, which might contain 10-20% impurities that can’t be used for water softening.

Using lower-purity salt (such as rock salt) will also increase how often you’ll need to clean the brine tank because the impurities are unable to dissolve in water, so they’ll end up clogging the bottom and sides of the tank.

Salt Vs Potassium Chloride

If you use potassium chloride pellets in your water softener, you’ll need to top up the salt tank more frequently than if you used salt pellets.

Potassium chloride is slightly less effective in a water softening system than salt. Manufacturers recommend that you increase your water hardness setting by 25% to compensate, so you still get complete water softening when using this mineral.

Because your water hardness setting is higher, the amount of “salt” used is also higher, so the brine tank will become depleted at a faster rate.

Sodium chloride vs potassium chloride

Water Hardness

Your water hardness levels will also determine how much salt your water softener system uses, and how frequently you’ll need to top up the salt in the brine tank.

The harder your water, the greater your water softener’s salt usage. Every single hardness mineral in your water will be exchanged with a sodium ion – so the more hardness minerals, the more sodium ions used in ion exchange.

You’ll need to put salt into the water softener tank more frequently if you have very hard water.

HardnessGrains per Gallon (GPG)Parts per Million (PPM) & mg/L
Soft<1 0 – 17
Slightly Hard1.5 – 517 – 60
Moderately Hard3.5 – 7 60 – 120
Hard7 – 10120 – 180
Very Hard>10>180

Water Usage

Finally, your water usage also determines how much salt you need to add to a water softener, and how often.

Water softeners treat water on demand. So, if you use a lower amount of water per day than the average household, your water softener will treat less water and use less salt, compared to if you used an average or above-average amount of water per day.

The more water used, the higher the amount of salt used in the ion exchange process per day. Thus, the salt in the brine tank would become depleted at a faster rate.

Filling a glass of water from a sink faucet

📝 Tips For Adding Water Softener Salt To Brine Tank

When you add salt to a water softener brine tank, keep these tips in mind:

Check For Salt Bridges

Before you pour a fresh layer of salt into the brine tank, check that there’s no layer of encrusted salt – known as a salt bridge – covering the top surface of the salt level.

If there is, break up the salt bridge with a broom handle and pour hot water into the tank to break up the salt. Fish out the salt chunks with a net or a bucket.

Use Proper Water Softener Salt

Make sure to use salt that’s specifically designed for water softeners in your brine tank.

Not only will other types of salt dissolve less effectively in your water, but they might also fail to soften your water properly or be unsafe for consumption.

If a salt product is made for water softeners, it should clearly state “water softener salt” on the packaging.

Putting salt in a water softener

Use High-Purity Salt

The higher the salt purity, the longer it should last, and the cleaner the brine tank will be. We recommend evaporated salt, which has 99.7-99.99% purity on average. Solar salt is another good choice, with a purity of around 99.5-99.8%.

While evaporated salt and solar salt cost a bit more than low-purity salt (like rock salt), you should get more value from each bag of salt because the percentage of salt is higher.


How do I know when to add salt to my water softener?

You’ll know when to put salt into your water softener by looking in the brine tank. If the tank looks dry and it’s less than half-full of salt, it needs a top-up.

Can you overfill a water softener with salt?

Yes. Most water softeners have a maximum fill level in the brine tank. If you exceed this level, you’re more likely to have issues with encrusted salt and salt buildup. This buildup will prevent your water softening system from properly performing a regeneration cycle.

How many bags of water softener salt do I need?

The average family of four needs 1-1.5 40-pound bags of salt per month. Your water usage and hardness affect exactly how much salt you’ll need.

Why does my water softener salt tank look full?

If your water softener salt tank looks full but you haven’t topped up the salt for weeks, you might have a salt bridge. This compacted layer of salt forms over the top of the remaining salt in the tank, making it look like the tank is still full. Gently press the salt with a scoop or a broom handle. If the salt doesn’t move easily and appears to be stuck together in a block, you’ll need to break it up and remove it from your tank.

  • Brian Campbell
    President & CEO, CWS, CWR

    Brian Campbell, a WQA Certified Water Specialist (CWS) and Certified Water Treatment Representative (CWR) with 5+ years of experience, helps homeowners navigate the world of water treatment. After honing his skills at Hach Company, he founded his business to empower homeowners with the knowledge and tools to achieve safe, healthy water. Brian's tested countless devices, from simple pitchers to complex systems, helping his readers find the perfect fit for their unique needs.

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