How a water softener works – mystery solved!

by Stuart P Published 6.13.2012

In the world of home appliances, there are few more mysterious than the water softener. Most other appliances give blatant clues as to what they do. A blender puts its handiwork out there for us to detect with loud noises, swirling liquid visions, and conversation-worthy tastes. The furnace heats you up, the A/C cools you down, the leaf blower, well, it moves things around. Softeners are much more subtle as they serve silently in some inconspicuous location.

Why would you ever want to buy a mysterious silent appliance that lives on a diet of salt nuggets? Many people never make the connection and so they endure the effects of hard water without ever really knowing there was a solution. They take things like bathtub ring as a natural part of life. It is actually the product of a reaction between soap and dissolved minerals in the water. The technical term is soap curd. Yes, just like in the famous poem featuring Miss Muffet. A softener exchanges the dissolved calcium ions for sodium or potassium so this reaction can’t happen.

The softener accomplishes this amazing feat through a process called ion exchange, and it follows the physical laws of electrical attraction and chemistry. Just like the opposite ends of two magnets attract each other and the similar ends repel each other, ions seek to find their proper place as they float around dissolved in water. Ions are charged particles, so some have a positive charge of varying degree, and others have a negative charge.

A classic example of ionization can be seen in table salt, also known as sodium chloride or NaCl. When dissolved in water, the sodium atoms turn into positive ions by giving up a negative electron to the surrounding water. The chlorine atoms gain an electron, and in so doing they turn into negatively charged ions.

The media inside the softener uses this principle of opposites attracting each other. It is specially made to have a chemical structure with permanently ionized docking sites to attract and hold positive ions. These docking sites start out loaded with sodium or potassium ions from the salt regeneration process. When hard water passes by on the way to your faucet, the docking sites take on the hardness ions because the attraction is stronger. The ions from the salt are released in exchange, and the result is softened water. I have uploaded a video to this blog to help explain this process—please note the accomplished actor in the video :)

View this video on Kinetico's YouTube channel

Hopefully some of the mystery is gone, and you can better understand how softening works and some of its benefits. 

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About the Author

Stuart P
Stuart P

From my earliest memories I have had a fascination with water. The highlight of summer was going to a place called Wheeler’s pond. Birds, frogs and dragonflies ruled, and if you stood still in the shallows long enough, the bluegills would come and nibble on your shins. Sunday nights the family would watch Disney, Wild Kingdom, and with heightened interest there would be the Jaques Cousteau specials. I could think of no better life pursuit than to be like Albert Falco, his chief underwater cameraman. The best vacation of my young life was to Cape Hatteras, where the waves at that time towered over my head, menacing and cold, yet they lured me ever closer.

I graduated from The Ohio State University with a degree in mechanical engineering. After passing the test to become a registered Professional Engineer, I began to wonder how I ended up here. All my ancestors were smart in different fields, but no known blood relatives of mine were ever engineers. I was the kid who wasn’t afraid to take things apart. Clocks, bikes, toys, lawn mowers, toasters, blenders, washing machines; they were all fair game. What was truly astounding was when I could get them back together again. Even now I figure if some device is broken, cast aside, or if no one is watching, what’s the harm in doing some exploratory disassembly?

Today my interest in water not only includes the recreational and beauty-of-the-earth aspects, but also the practical. As water enters the home, in addition to its most valuable property of being wet, it often has characteristics that we would rather it not. Hardness, iron, bad smells and tastes in your tap water are things that technology can greatly improve. The invention, improvement, manufacturing and application of these technologies have occupied me the past 22 years of my life. Water treatment equipment is one of those things that when it is working best, most people don’t even realize it. It’s that goal that drives innovation.