A water softener is a type of water filtration system that reduces or reformats calcium and magnesium minerals in water to reduce water hardness.
How salt-based & salt-free water softeners work
A water softener works in one of two different ways, depending on the softening technology it contains.
In a salt-based water softener, tiny amounts of sodium or potassium are used to attract and swap places with the hard minerals.
In a salt-free water conditioner, an electromagnetic charge is used to crystallize hard minerals so that they cannot bind to surfaces and form scale or mineral deposits.
In other words, a salt-based water softener works by removing calcium and magnesium, while a salt-free conditioner changes the format of these ions. Salt-based softeners can handle harder water, and work better as water softeners for well water, as wells contain more hard minerals.
What does a water softener do?
Calcium and magnesium ions interfere with the way soaps and detergents work. They also create dry skin and hair by affecting the oil barrier. As a result, using a water softener to reduce or reformat the minerals:
- makes detergents more effective at removing dirt and stains from clothing or dishes,
- gives water a softer, more moisturizing feel,
- allows you to use less detergent or soap to achieve the same cleaning results.
What is a salt-based water softener?
Most water softeners use a salt-based process to soften water. Here’s the science behind the technology and the steps that happen inside a softening system.
How do salt-based water softeners work?
Salt-based water softeners used a process called ion exchange to soften water. Ion exchange occurs when ions with the same or opposing electrical charges are placed next to each other.
Inside the softener tank is a resin bed made of porous plastic that’s coated with a salt-brine solution. This solution is designed to attract hard mineral ions from your water and exchange them with soft salt ions.
Sodium or potassium ions have a positive charge—this gives the entire resin bed a positive charge.
The calcium and magnesium ions that exist in hard water also have a positive charge. When hard water through the softener system, these ions stick to the resin bed.
The resin bed wants to retain the same electrical charge, so it pushes the sodium ions into the water. In other words, the salt ions are exchanged with the hard mineral ions.
The size of the resin bed determines how many hard water ions can be exchanged with soft salt ions at any single time. Resin beds are usually measured in cubic feet.
What does a salt-based water softener do?
Here are the basic steps that happen inside a water softener to turn hard water into soft water:
1. The water softener collects your water supply
Water softeners are installed on the main water line at the earliest point in a home’s water supply. As hard water passes through the main pipe, it will enter the softener system long before it gets to faucets or showers.
2. The water enters the mineral tank and passes through the resin bed
The resin beads inside the bed attract any hard minerals in the water and exchange them for soft salt ions. This process requires no moving parts or electricity.
3. Soft water flows into your house
Once the water softener has removed calcium and magnesium ions and replaced them with sodium, that soft water flows out of the mineral tank and enters your home plumbing.
4. The water softener regenerates
Over time, all of the salt ions contained in the resin bed will be exchanged for hard water ions. Once the bed becomes saturated with magnesium and calcium, the softener system will need to regenerate the bed in order to function.
Some water softeners regenerate on a timed basis. Others contain microprocessors and sensors so to regenerate on demand.
The softener will wash the mineral tank with a new supply of salt brine, cleansing the resin bed and resetting the ion charge. When a softener regenerates, it goes into an inactive state and cannot soften water during that time.