How a water softener works || Ion Exchange



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Home > Water Quality > Water Treatment Strategies > How a softener works

How a water softener works

We are often asked why passing water through salt makes water better. The truth is that the water does not pass through the salt container.

The salt in a water softener system serves only to occasionally restore its capacity. We hope that you find the explanation below helpful. Our full-service division sells and services softeners as well as other water quality improvement systems.

Softening water is a 4-step process.










1) The body of a water softener is a tank filled with resin beads.These beads are covered with sodium (or sometimes potassium) ions. As hard water passes through, the resin beads act like a magnet, attracting calcium, magnesium, iron and manganese ions (hardness) in exchange for the sodium or potassium ions. The ion exchanged depends on the type of regeneration salt or salt substitute placed in the brine tank. In some cases we recommend a salt additive to minimize iron fouling of the beads.

2) Eventually the resin beads become saturated with mineral ions and have to be "recharged".   This process is called regeneration, and is conducted by the control valve which is usually on the top of the tank. The control valve is the brain of the system. Some control valves regenerate on a preset time schedule while others are triggered by volume. Newer electronic systems are programmable for both.

3) During regeneration, a strong brine solution is flushed through the resin tank, bathing the resin beads in a stream of sodium ions which replace the accumulated hardness ions. Precipitated iron is both backwashed away and dissolved by salt additives.

4) The brine solution, carrying the displaced nuisance mineral ions, is then flushed down the drain by fresh water. The regenerated resin beads can be used again and again. Often water softeners operate over 10 years before the beads (or the entire system) need to be replaced.

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