How does a water softener work

There are many methods of water softening that allow you to deal with water “hardness”. Four methods have become among the most desired: ion exchange, reverse osmosis, electronic and magnetic methods. Each water softening method has positives and negatives, but all work to eliminate hard water from your home.

Ion Exchange

Using the ion exchange method, also referred to as the salt-based method, a pressure tank is installed and filled with negatively charged ion exchange resin, or sodium ions. Each time water passes through this exchange site, the resin’s attraction for the positively charged “hard” ions of magnesium, calcium and iron causes it to take on the hardness ions and give up its sodium ions, thus creating an ion exchange in which only soft water flows. All ion exchange systems have an automatic regeneration cycle in which an upward flush of water, called backwash, loosens the resin bed and flushes out resin particles so that the sodium ions are again ready to take on hard water ions. The main concern of the ion exchange method is that sodium remains in the soft water, which may be harmful to those on sodium-restricted diets and present an unpleasant taste. As a result, water processed through ion exchange systems is not recommended for drinking, houseplants or gardens due to the high salt content. In either case, however, a separate water dispenser may be installed or potassium chloride may be used in place of salt. This method is among the most assured, but it does require maintenance to both monitor and refill the tank with salt, or potassium chloride, about every 2 months, depending on how much water is used. This method also requires professional installation.

Reverse Osmosis

Reverse osmosis systems provide you with salt free water that is removed of hard minerals. The process forces water under pressure through a semi-permeable membrane that allows water molecules to pass through, trapping larger molecules such as calcium, magnesium and iron. Reverse osmosis water softening can be used in conjunction with salt-based water softening to remove salt that has been left in a water supply. However, this method wastes up to 15 percent of water through a flushing process in order to keep the membrane clean and requires maintenance of the storage tank to ensure that it is free of bacteria build-up. One great benefit of this method, though, is that there is no limit to the amount of water’s “hardness” it can handle.


Electronic water softening works without salt, chemicals or changes to plumbing. It is also often referred to as the salt-free method of conditioning. Mounted onto your pipes is an electromagnetic device containing a computer chip. This computer chip is programmed to bombard water passing through your pipe with hundreds of electromagnetic low frequency pulses. These electromagnetic pulses increase the electromotive attraction of water to minerals so that the calcium bicarbonate dissolved in your water supply does not turn into calcium carbonate, which attaches to pipes and creates scale. Technically, electronic water softening does not remove minerals from your water supply, but alters them so they do not form scale. This method is easy to use and solves the problem of scale without added sodium to your water supply, but is not ideal for homes with extreme hard water problems.


Magnetic water softening, or magnetic water treatment (MWT), relies on strategically placed magnets surrounding pipes to extract the minerals from the water, namely calcium, magnesium and iron. Magnetic water softening is ideal for apartments or single-family homes where space does not permit the installation of a whole house water softener. However, the limitations from this method include having pipes made of weak material, such as copper or plastic. In addition, water goes back to a hard state within 48 hours of leaving the magnetic field and in order to become soft again, it must pass by the magnetic field. Magnetic water softening is among the least expensive techniques.

Brands like Culligan, Ecowater and Kinetico are leaders in the industry of water softeners and conditioners and offer water testing, system installation and service.