Most home softeners use a process called ion exchange. It happens in three simple steps.
1
Hard water flows in
Water carrying dissolved calcium and magnesium enters a tank filled with small resin beads.
2
Minerals are swapped out
The resin beads grab calcium and magnesium and release sodium (or potassium) in their place. Soft water flows to your taps.
3
The system recharges
When the beads fill up, the softener flushes them with salty brine from the brine tank, rinses the minerals down the drain, and starts again.
Your options
Types of Water Softeners
Not every system that is sold as a "softener" actually removes hardness. Here is what each type really does.
Most common
Salt-Based (Ion Exchange)
Removes calcium and magnesium for true soft water. Needs salt refills and a drain line. Best for hard and very hard water.
Low maintenance
Salt-Free Conditioner
Usually uses TAC media to change minerals so they are less likely to form scale. Does not remove them, so you won't get the soap and skin benefits of soft water.
Big households
Dual-Tank Softener
Two resin tanks take turns, so you always have soft water, even while one tank regenerates. Useful for large families or very high water use.
Limited evidence
Magnetic & Electronic
Clamp-on devices that claim to reduce scale using magnets or electric signals. Independent evidence is mixed, so we treat these claims with caution.
Check your home
Do You Need a Water Softener?
If you notice two or more of these signs, it is worth testing your water hardness.
White, chalky scale on faucets, shower heads and glass doors
Spots and film on dishes and glasses after washing
Soap and shampoo that don't lather well
Dry, itchy skin or dull hair after showering
Stiff, scratchy laundry and faded colors
Scale build-up shortening the life of your water heater
Dry skin & hairSpotty dishesStiff laundry
Test before you buy: use a home test strip or check your water utility's annual Consumer Confidence Report.
Water hardness scale
How Hard Is Your Water?
Classification
mg/L (ppm)
Grains per gallon
Soft
0 – 60
0 – 3.5
Moderately hard
61 – 120
3.5 – 7
Hard
121 – 180
7 – 10.5
Very hard
Over 180
Over 10.5
Classification based on the U.S. Geological Survey (USGS). 1 grain per gallon = 17.1 mg/L.
Quick sizing rule
What Size Water Softener Do You Need?
Softeners are rated in grains: how much hardness they can remove before they need to regenerate. A simple way to estimate your daily need:
People in your home × 75 gallons × hardness (GPG) = grains per dayExample: 4 people × 75 × 10 GPG = 3,000 grains a day, or about 21,000 grains a week. A 30,000 to 40,000-grain softener would usually cover that with room to spare.
Have iron in your water too? Add about 3 to 5 GPG for every 1 ppm of iron, and always check the manufacturer's sizing guide.
Side by side
Salt-Based vs Salt-Free
The biggest decision most homeowners face.
Salt-Based Softener
Salt-Free Conditioner
Removes hardness minerals
Yes
No (reduces scale only)
Better soap lather & softer skin
Yes
Little to no change
Ongoing cost
Salt refills, some water for regeneration
Media replacement every few years
Drain line & electricity
Usually needed
Usually not needed
Adds sodium to water
A small amount
No
Best for
Hard to very hard water
Moderate hardness, low maintenance
Some cities and counties restrict salt-based softeners because of the salty discharge. Check your local rules before buying.
Guides
Essential Water Softener Guides
In-depth, step-by-step guides for every stage, from testing your water to keeping your softener running.
A well-maintained salt-based softener often lasts 10 to 15 years or more. The resin may need replacing sooner if your water has chlorine or iron. Keeping the brine tank clean and using good-quality salt helps it last longer.
Can I drink softened water?
For most healthy people, yes. Salt-based softeners add a small amount of sodium, rising with how hard your water was. If you are on a low-sodium diet, talk to your doctor, use potassium chloride, or drink from a reverse osmosis tap.
Does a water softener remove contaminants?
No. A softener removes hardness minerals and can remove small amounts of iron, but it is not a filter. To remove chlorine, lead or other contaminants, you need a filtration system certified for those contaminants, such as an NSF-certified filter.
How often does a softener regenerate?
It depends on your water hardness, how much water you use, and the softener's capacity. Many homes regenerate every few days to once a week. Metered softeners regenerate only when needed, which saves salt and water.
Not sure what your home needs?
Send us your question and we may answer it in an upcoming guide.
Most common
Low maintenance
Big households
Limited evidence
