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Home » Water Softeners » When To Add Salt to Water Softener and How Much to Add

When To Add Salt to Water Softener and How Much to Add

By: Craig Smith
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When To Add Salt to Water Softener and How Much to Add

If you have a salt-based water softening system in your home, then you no longer must worry about cleaning stubborn limescale off bathroom fixtures and the other problems that having hard water causes.

But remember to keep in mind that your water softener does need some minor maintenance from time to time to keep you in that hard water mineral free state.

That includes maintaining the proper salt level in your water softeners brine tank.

One of the biggest concerns that water softener owners like you have is when to add salt to water softener and how much to add.

I will use my many years of water filtration experience to answer both questions and give you some other practical information about water softeners too.

Understanding How Your Water Softener Works

First of all, I want to talk about why having enough salt in your water softener’s brine tank is so important to its operation.


Water softeners work by utilizing a process called ion exchange. In the photo above you will see a typical salt-based water softener setup.

The cylindrical tank on the left is the main tank (also called a resin tank) where the ion exchange process takes place.

The shorter and wide tank to the right is the brine tank. This tank stores a salt solution (also called brine solution) that enables the hard water mineral removal ion exchange process to take place.    

Before the ion exchange process in your water can take place the salt solution in the brine tank is pumped into the main tank that contains thousands of resin beads.

These beads are placed in the bottom of your water softener’s main tank to form a resin mesh bed. When the brine solution enters the resin tank, positively charged ions in the salt solution stick to the negatively charged resin beads.

After that process is complete, your incoming water that has hard water minerals present in it is then allowed to enter the resin tank.

Hard water minerals have stronger positively charged ions than those of your salt solution. Because of this, they exchange themselves with the salt ions coating the resin beads.

Periodically, your water softener will run another regeneration cycle which not only refreshes the salt in the main tank but also cleans the trapped hard water minerals off the resin beads.

So, by not having enough salt in your brine tank to make a proper salt solution for the ion exchange process, it makes your water softener less impactful when it comes to removing hard water-causing minerals.  

That’s why if you own a water softener, you must take steps to ensure the salt in the brine tank is kept at the recommended level.

When and How Often to Add Salt to Your Water Softener

You will need to add new salt to your water softener about once every month or two or when the automatic indicator notifies you if you have a high tech softener.

You will need to add salt to your water softener when the level of the salt in your brink tank is more than 6” below the marked fill level on the inside of that tank. 

If this is the case, then top-off the salt level.

As a general rule, you do not have a fill level indicator marked on your salt tank, use the hallway point of your brine tank as an approximate fill level.

This question of how often you add salt to your water is somewhat hard to give you an exact answer on.

That’s because there are so many different water softener models, and they have different rates of salt usage.

For example, an upflow-style water softener will use 30% to 60% less salt than a downflow-style water softener.

The best way to tell when salt needs to be added to your water softening system is to periodically check the salt level in the brine tank.

Start doing this every two weeks and then as you get used to the timeframe your water softening salt is being used up at, you can adjust this schedule.

It will probably be the case with most modern water softeners that you will not have to add salt to them more than once a month unless you have extremely poor quality well water.

Again, when doing the inspection, your salt level should be within 6” of the fill level marked on the brine tank (or the halfway point of the salt tank). If not, then salt needs to be added to the tank.

If you have a programmable control head on top of your water softener’s resin tank, it can help you out with this process.


Most water softener programmable control heads will alert you to when it’s time to check the system’s salt level or they can be set to remind you to inspect your brine tank’s salt level at preset intervals.

Keep in mind that even the best water softeners, no matter how efficient they are, will still need to have salt added to their brine tanks periodically.

How Much Salt Do You Put in A Water Softener?

You will need to fill your brine tank to the manufacturers marked line that specifies that amount of salt your softener needs.

Many companies that make water softeners have been at it a long time. That allows them to develop their systems in a way that makes them easier to use.

Part of this is that nowadays most manufacturers will have a clearly marked line somewhere near the middle of their brine tanks.

This line is placed there so users like you will be able to clearly see the level where your water softener salt should be at all times.

No, that does not mean you have to check the salt level every day and keep it exactly there, but you should check your water softener’s salt level every 2 weeks or so.   

If you do not have a clearly marked fill point on your salt tank, then the halfway point of the tank can be used as a fill reference. This salt level will work nicely for almost every model salt-based water softener that’s made.  

How To Add Salt to Water Softener

Your brine tank is easily identifiable because it has a lid on it that’s easy to open. Once you take the lid off, you will need to perform the following steps to top off the salt level.

Step 1: Make sure that your brine tank is in good condition. That means there should be no salt bridges, salt clumps, and it’s not full of dirty residue that can cause valve and injector clogging.

If any of these conditions are present, I recommend that you drain, empty, and clean your salt tank before you add fresh salt to the system.

Salt tanks are made of less rigid plastic. Sop be careful not to damage them when you are cleaning them.

Step 2: Place a salt bag on the floor next to the brine tank and make a triangular cut at on of the top corners that’s about 4” long.

Step 3: Note where the fill line is on your water softener brine tank. If there is none, then note the approximate location of the halfway point of your salt tank.    

Step 4: Add as much salt as is necessary to fill to the noted point in step 3.

Step 5: I like to add salt until it’s an inch or two over the marked fill line or halfway point of the tank to allow for settling.

Keep in mind that salt bags are around 40 to 50 lbs. apiece. So, lugging them from the store to your home and then pouring them into your brine tank is not always easy for everyone.

If you live in a large enough city, then you can probably find a service to deliver water softener salt to you. When you contact them for this, you may also want to inquire if you have an option for them to add the salt, if necessary, too.  

What Type of Salt Is Best to Use?


You have several different options to choose from when you are looking to purchase salt to use in your water softener.

Here are the 4 most popular types of water softener salts:

  • Rock (sodium chloride)
  • Evaporated (sodium chloride)
  • Solar (sodium chloride)
  • Potassium chloride  

All of them will work as an integral part of your water softener’s ion exchange process but some will perform better than others.

While rock salt is the cheapest of all the water softener salts that are available, I would avoid it because it has too many impurities. These impurities can cause problems with the inner workings of your water softener

Both solar salt and evaporated salt contain very few impurities and those are what I recommend that you use in your water softener.

Potassium chloride is a more expensive form of salt. It’s usually recommended for purchase to use in a water softener if your doctor has told you to eliminate as much sodium chloride as possible from your diet.

Some Final Words on Adding Salt to Your Water Softener

Hopefully, after reading this article you should have a much better understanding of how your salt-based water softening system works.

Because of that, you will also understand the important role that salt plays in helping your water softener do its job properly.

That’s why it’s so important to figure out a schedule to check the salt level in your water softener’s brine tank periodically and to take corrective action if your salt level is too low when you inspect the tank.

This is not that hard to do and if you don’t do it, then you may negate all the advantages that your water softener offers when it comes to removing problematic hard water minerals.  

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Craig Smith
Craig got his start in water working in the swimming pool and spa industry. Water treatment would grow into his main career but he ended up working in the pool industry for over 26 years where much of his time was spent balancing the water in customer's swimming pools and installing water filtration equipment. Craig offers an abundance of water treatment knowledge after helping homeowners get pure water for 26 years.

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