How Much Salt Does a Water Softener Use?

Most water softeners use about 30-60 pounds, or around 1-1.5 40-pound bags of salt, per month.

The amount of salt your water softener uses depends on the system type and size, your water consumption, and the water softener’s regeneration schedule.

🧾 How to Calculate Water Softener Salt Requirements

To get a more accurate estimation of how many bags of salt you will use per month in your water softener, follow these steps.

What you need to know in advance: 

• No. of people in your household
• Your water hardness (in grains per gallon or GPG) 
• Your required water softener’s grain capacity
• Your water softener’s required salt dosage in pounds per cubic feet (lbs per cu. ft), which should be provided by the manufacturer

To calculate your water softener salt requirements, here’s the 5-step formula you should use: 

1. Calculate the water softener’s run length in gallons. Resin capacity (grains) / total hardness (grains per gallon) = N
2. Subtract the reserve. N – (70 (gallons used per person) x no. of people) = X
3. Calculate the number of days between water softener regenerations. X / total gallons per day = Y days
4. Determine the number of system regenerations per month (assuming there are 30 days in the month). 30 days / Y days = Q regens per month
5. Calculate number of bags of salt required. Q regens per month x required salt dosage = no. of lbs per month

You can then compare this figure to the weight of a standard bag of water softener salt (45 lbs) and multiply the number by 12 to determine the average number of bags of salt you’ll need when you compare the weight in lbs. 

Example Calculation for Water Softener Salt Requirements

Let’s say that you have 3 people in your home and a water hardness of 18 GPG. Your required water softener’s grain capacity is 20,000 grains and the salt dosage for this system is 6 lbs/cu. ft. 

Here’s how you’d calculate your water softener’s salt requirements: 

1. Calculate the water softener’s run length in gallons. 20,000 grains / 18 GPG = 1,111 gallons
2. Subtract the reserve. 1,111 – (70 gallons used per person x 3 [no. of people] = 210) = 901 gallons
3. Calculate the number of days between water softener regenerations. 901 gallons / 210 gallons per day = 4.3 days. Round down to 4. 
4. Determine the number of system regenerations per month (assuming there are 30 days in the month). 30 days / 4 days = 7.5 regens per month
5. Calculate number of bags of salt required. 7.5 regens per month x 6 lbs (required salt dosage) = 45 lbs per month. 45 x 12 (months in the year) = 540 lbs per year. 

We know that most water softener salt bags are 40 lbs. So, to determine approximately the number of salt bags we need per year, we can divide 540 by 40, which makes 13.5 bags. 

📰 Factors Affecting Water Softener Salt Usage

There are a few factors that affect how much salt a water softener uses. These are:

• Your water hardness: The harder your water (aka the more calcium and magnesium ions it contains), the more sodium needs to be exchanged during the softening process. If your water is very hard, your softener will use more salt than if you have moderately hard water.
• Your water usage: The more water you use per day, the more water will need to be softened. If your daily water usage is higher than average, your water softener usage will be higher, and so will your salt usage.
• The type of salt: Different water softener salts are used at different rates depending on their purity. Evaporated salt is most efficiently used by your water softener because it’s the purest softener salt available. Solar salt and rock salt have a higher concentration of impurities and less salt, so they’re used less efficiently.
• Whether you use sodium or potassium: Potassium chloride (an alternative to sodium for water softeners) isn’t as effective as salt, so you should set your water hardness to 20%-30% higher when adding potassium chloride to the salt tank. This means your water softener will use 20-30% more potassium chloride than salt.
• Your water softener’s regeneration type: There are two types of water softener regeneration cycles: timer-based regeneration and demand regeneration. Timer-based softeners are typically less efficient and waste more salt than demand softeners because they regenerate based on the time passed rather than water usage.
• The age of the water softener: Older water softeners lose their softening efficiency and may waste more salt during regenerations. Softeners over 10 years old aren’t designed as efficiently as the newer models, either. Older softeners use more salt than modern, efficient water softeners.

Related: The most high-quality salt that’s ideal for water softening systems

🚰 How to Conserve Water Softener Salt

There are a few ways to use less salt in your water softener and save money on salt top-ups in the long run:

Buy a High-Efficiency System

Some of the best water softeners today use efficient softening and regeneration processes to reduce their salt usage.

These processes include:

• Smart brining, which calculates exactly how much brine solution is needed for a regeneration cycle, preventing salt waste.
• High-capacity brine and resin tanks, reducing the frequency of regeneration cycles.
• On-demand regeneration, meaning that the system regenerates based on water usage and not at a set time per day.

Reduce Your Water Use

Reducing the volume of water used in your home will also reduce your water softener salt usage.

Be mindful of your water usage. Switch off your faucet when you’re brushing your teeth, replace inefficient fixtures, and fix leaking taps and pipes.

Consider a Saltless Water Conditioner

But if you’re still considering your options, consider a salt-free softening alternative, like a water conditioner.

Water conditioners don’t need salt, so you can eliminate your need for salt entirely.

🧠 Water Softening Salt Usage FAQs

How long should a bag of water softening salt last?

A 40-pound bag of water softening salt typically lasts around 1 month for the average family of 3-4. However, this depends on the size of the bag, the type of salt, the efficiency of the softening system, the size of the brine tank, your water hardness – and more! You should add salt based on your own observations and the information in your user manual.

How much salt does it take to regenerate a water softener?

The amount of salt it takes to regenerate a water softener depends on your water softener’s size, but most water softeners use 6-15 pounds of salt (dissolved in water as brine) per regeneration cycle. If your water contains iron, your softener may use more salt per regeneration.

How can I tell if my water softener is using too much salt?

You’ll tell if your water softener is using too much salt if you’re topping up your salt levels noticeably more frequently than before. Most water softeners need around one 40-pound bag of salt per month, so if you’re using significantly more than this and can’t pinpoint a reason, you might need to troubleshoot the system.