How a Water Softener Works

How a Water Softener Works : Cation-exchange Water Softener

In general water with 0 to 3.5 GPG is considered safe and soft. Anything above this is considered hard water. The contents of hard water are mainly calcium, magnesium and iron. Hard water can be softened with a water softener. But how a water softener works to soften hard water?

Well, the principle behind a water softener is quite simple. The calcium and magnesium ions in the water are replaced with sodium ions. Sodium has the property of not to prec­ipitate in pipes. Sodium also does not react with soap. This helps to eliminate hard water problem.

Typical Water Softener

A typical water softener works more or less like a Cation-exchange water softener. It has a resin tank that accommodates resin beds (made out of beads of styrene and divinylbenzene) arranged in columns. These resin beads attract the mineral ions of hard water and gives off sodium ions.

There is a brine tank to recharge the beads with sodium ions. All this process is controlled by several controls in the unit.

Whole House Water Softener

Standard whole house water softener works on the principle of ion exchange. This phenomenon is called “cation exchange.”

What is actually does is that it just replaces / substitutes for hard minerals such as calcium, magnesium, and iron with sodium chloride salt / sodium ions and conditions hard water.

Cation-exchange Water Softener

A cation-exchange softener has a housing called “resin tank”. This tank accommodates resin beds arranged in columns. Water flows through this plastic-like resin beads. These resin beads attract the mineral ions of hard water and gives off sodium ions. Rest of the water softening work is done by these sodium ions.

These beads have to be periodically recharged with sodium ions. To do this, they are flushed with salt water (brine). This process removes hard mineral ions from the resin and discharges them as waste. Once excess sodium is rinsed away, the cycle is repeated.

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