How Softeners Work

At right is a diagram of our Fleck 5600 Softener. It shows how our softener—and everyone else's softener—works.

A water softener is an ion exchanger. Hard water—water with a high calcium/magnesium content—enters the softener through the “In” port indicated by the green arrow. It passes through the control valve and into the tank, where it goes from top to bottom through a specially prepared resin that “softens” it.

The resin consists of beads that have been specially manufactured to be saturated with sodium ions. “Softening” occurs as the hardness minerals in the water attach themselves to the resin and are “exchanged” for sodium.

The softened water then enters the long center tube, called a riser, via the strainer basket in the bottom of the tank and passes upward through the riser. The water exits the softener via the control valve (blue arrow) and is sent to the home.

When the resin becomes saturated by hardness minerals, the softener automatically goes into regeneration. (The regeneration process is initiated by a timer or a meter, depending on the type of softener you purchase.) By this process the hardness minerals are washed down the drain (via a drain tube not shown in the diagram), and the resin bed is rinsed, resettled, and recharged with sodium. It is now again ready to soften your water.

The regeneration process is accomplished by passing very salty water from the brine tank through the resin.

The brine tank must remain filled with softener salt at all times so that it can regenerate the softening resin again and again.


Hardness. The concentration of calcium and magnesium salts in the water.

Ion Exchange. A chemical reaction in which ions are exchanged in solution.

Regeneration. The process by which an ion exchanger (like a water softener) renews its ability to do its job. This is carried out using either an acid or alkali to remove the accumulated actions or anions, respectively. At the same time, the action exchanger takes on hydrogen ions to restore themselves to the original hydrogen or hydroxide form, respectively.

Resin. Specially manufactured polymer beads used in the ion exchange process to remove dissolved salts from water.

Soft Water. Water containing less than 17 PPM calcium or magnesium.

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