How Water Softeners Work

  • 01 of 07

    Understanding Water Softeners

    Water softener
    BanksPhotos / Getty Images

    Describing how water softeners work often involves words you don't hear very often. Since water softeners do their work largely through chemistry you may hear the words “ion” and “ion exchange” and “resin”.

    This overview is going to attempt to make the explanation a lot simpler and straightforward because understanding how water softeners work should not be a mystery or require attending a chemistry class. Since these appliances are important and expensive, understanding how they work is just a good thing to know.

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  • 02 of 07

    What Is Hard Water?

    Tap limescale. Selective focus on the hard water deposit of a running kitchen faucet.
    Ian Dyball / Getty Images

    Hard water is a generic term that means groundwater has picked up minerals from the earth such as magnesium and chalky calcium. Water with high levels of calcium can clog pipes with mineral build up left behind as the water flows through the pipes.

    Hard water also reduces the ability of soap to lather and the minerals form a sticky scum with the soap and prevent easy rinsing of anything being washed. This includes your hair, your car, and your dishes and glasses with water spots. They all will have a white chalky scale or residue left behind with hard water.

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  • 03 of 07

    What About Rotten Egg Smelling Water and Rust Stains?

    High Angle View Of Broken Egg Shells In Crate
    Silvia Elena Castañeda Puchetta / EyeEm / Getty Images

    Other minerals can be found in the water beside manganese and calcium, especially if you have a well as your water source.

    For example, ferrous iron is a common mineral and it creates nasty rust stains in sinks, tubs, and toilets. Manganese causes black staining and is often found with iron.

    “Rotten egg” smelling water is caused by hydrogen sulfide gas. All these problems and more can be filtered out of your water with special water treatment softening systems, but a standard water softener will not take care of these problems. You must have a water treatment system designed for eliminating these additional minerals.

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  • 04 of 07

    What Is a Water Softener?

    Water Softener Components

    The water softener is just a special type of "filter" that removes the calcium and magnesium in hard water by using plastic beads and cleans itself periodically by a process called “regeneration.”

    Water softeners have three main components: A mineral tank, brine tank, and control valve. Smaller capacity models combine the mineral tank and brine tanks into one cabinet, but the two tanks are still separated within the cabinet.

    Larger flow capacity systems have a separate stand-alone mineral and brine tanks:

    • Mineral Tank: The mineral tank is where the action is. It is where the water filtration takes place and the hard water is softened (calcium and magnesium are removed).
    • Brine Tank: The brine tank is where a highly concentrated solution of salt or potassium is stored.
    • Control Valve: The control valve is the device that controls the flow of water into and out of the mineral and brine tanks during regeneration.
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  • 05 of 07

    The Mineral Tank (Water Softener)

    Mineral tank

    The mineral tank is where water is softened and incoming hard water passes through media, a fancy name for plastic beads. These beads are often made of polystyrene and may also be called resin beads or other names. At the end of the day, they are usually some type of plastic.

    The plastic beads have a negative charge and attract the calcium and magnesium minerals from the water which have a positive charge. Since opposites attract, electricity does the work for us and the hard water minerals are removed from the water and deposited on the plastic beads. The water is softened. Cool, huh?

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  • 06 of 07

    The Brine Tank

    salt blocks for softener
    DenBoma / Getty Images

    The brine tank is just what its name suggests, a plastic tank that contains a brine, water saturated with salt. The brine solution is typically made with salt or sodium. Problems may result if you are on a restricted low sodium diet in that some of the sodium is transmitted into the drinking water.

    The bacteria in septic systems so necessary for the breakdown of waste may be adversely affected by high concentrations of sodium. Water softener sodium brine discharge into septic systems has been banned or limited in several states and municipalities including Fillmore, CA, Michigan, Texas, and Connecticut for example.

    As an alternative, potassium may be used. Potassium is considered superior and environmentally friendly, albeit a bit more expensive, than salt and does not affect your health, watersheds, or the environment or your septic system.

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  • 07 of 07

    The Control Valve and Regeneration

    control panel water softener
    Aqua Mechanical/Flickr/CC BY 2.0

    The control valve is the traffic cop in your water softener system. It determines when it is time to clean those plastic beads which are now coated with calcium and magnesium. Older style units use a timer, newer models use a computer controlled meter that determines when it is time-based on actual water usage.

    To clean the beads, the water softener uses a process often called regeneration which consists of three cycles: backwash, recharge, and rinse. Let's take a review of each cycle:


    Regeneration starts with a backwash cycle where the valve reverses water flow in the tank and flushes the tank of debris. The debris is then eliminated out the drain.

    Recharge or Regeneration

    In the recharge cycle, the salty brine solution is pumped into the mineral tank. The highly concentrated salt solution with its positive electrical charge is attracted to the negatively charged plastic beads and forces the magnesium and calcium off the beads.

    The salt or potassium by itself is not positively charged enough to displace the magnesium or calcium in normal concentrations, but in the highly concentrated solution of brine, it is strong enough to force the calcium and magnesium off.

    The excess magnesium and calcium-rich salty water are then flushed out of the tank and down the drain.


    The tank is then filled and rinsed with water and the process repeats itself. The beads are now coated with salt. As the calcium and magnesium from the hard water are attracted to the plastic beads, the salt, now in much-diluted quantities and smaller electrical charge, is forced off the beads and is suspended in the softened water.

    When the beads become nearly all coated with minerals, the control valve starts a new regeneration cycle and cleans them again, flushing the hard water minerals down the drain.