How does a water softener work?

You may have already heard about hard water or water softeners and maybe about everything related to them too: the benefits of soft water, the related health issues, potential savings and other aspects, and if you are in this article then it is safe to assume you are interested in water softeners and maybe even also interested in getting one. But how does a water softener work? How do these devices take hard water and instantly turn it into softer water ready to use?

But before going straight to the explanations, why is hard water bad? Hard water is bad because it reduces the efficacy of soap and detergents, which will make you spend more water and more soap when taking a shower, and to wash your clothes, dishes and to mop of your floor; hard water will skyrocket your water consumption, and spending more water, detergents and soap obviously means more money spent. But besides the usual direct costs of using hard water, over time hard water can precipitate the formation of scales inside your pipes, clogging them and reducing your water flow or even completely blocking the flow of water, making a replacement needed; additionally, hard water can and will reduce the efficiency of your water heater so much that in a few years a heater may have a 50% less capacity and efficiency, which means that a heater used over time with hard water will require twice as much energy to make a half of the work, which will obviously mean more money you will have to spend.

Well, obviously it would also be important to first define what hard water is and what soft water is, and why is hard water bad; you may already know this, in which case you can skip this section and go directly to “The mechanisms behind water softeners”.


What hard and soft water are?

In very simple terms, hard water is water that has a high content of salts; and there are two particular types of dissolved salts that create most of the problems associated with hard water: calcium (Ca) and magnesium (Mg). These two are the salts that a water softener works to actively remove.

On the other hand, and as you may imagine, soft water is water with a lower and more acceptable level of dissolved salts in it.

The mechanisms behind water softeners

There are a few types of water softeners and each has its own mechanism; they are Salt-based water softeners, Salt-free water softeners and Magnetic conditioners.

  • Salt-based water softeners replace calcium (Ca) and magnesium (Mg) salts in water with chloride (Cl), which is harmless. They have a tank filled with lots of beads, all the salts in water are ions (particles with a magnetic charge which can be positive or negative) and each bead attracts ions. First, the beads are covered with chloride ions (which it gets from common salt provided by the user), then, when exposed to hard water, the magnesium and calcium ions in the water are attracted to the beads stronger than the chloride ions, so Mg and Ca they forcefully displace the Cl ions; that way the beads trap the Mg and Ca and let go of the Cl. When the beads are all filled with Mg and Ca and can take no more, the system goes into the regeneration phase: the beads are filled with brine (that the softener makes with the salt provided by the user), and the brine has so many Cl ions (since salt is Sodium Chloride) that the sheer amount of Cl ions displace the Mg and Ca ones; at the end of the regeneration, all that is left is some brine along with all the Mg and Ca ions the softener trapped dissolved in it, afterwards that brine is flushed down the drain.
  • Salt-free softeners do not really remove salts; they only chemically transform them from salts into crystals, rendering them permanently harmless. They will not require you to replenish salt and you just have to change its cartridges every few months, plus they also create no waste.
  • Magnetic conditioners are not true softeners because they do not remove the salts, they just render them harmless, just like Salt-free softeners, except Magnetic conditioners render them harmless but just temporarily. Magnetic conditioners consist of wire coiled around the intake pipe which creates a strong magnetic field that modifies the salts in water and renders them temporarily harmless and incapable of forming scale.

These are the mechanisms behind the current options in technology for dealing with hard water. As you can see, each one its advantages and disadvantages, and each one may work better than the other one for one particular situation and perform worse in others and only with a more in-depth analysis you will be able to decide which one is the best for you.


External links and resources