Water Softeners

Water Softeners Explained


A Brief Summary of Water Softeners

Water Softeners are required to extend the lifetime of plumbing by preventing corrosion. Similarly, it is an important preventative measure that eliminates scale build up. Primarily, it is the removal of calcium ions and magnesium ions, as well as other metal cations found in hard water.

An Overview of Water Softeners

Removing the calcium and magnesium ions from hard water is achieved with ion exchange resin. Ion exchange resin is typically made from sulfonated polystyrene. In addition, resin can be either positively charged ions (cations) or negatively charged ions (anions). Therefore, the charge of the resin in the softening vessel ultimately acts as a magnet. It causes the calcium and magnesium ions to become trapped on its surface.

But, when the resin is saturated, water softening vessels then exchange these calcium and magnesium ions for sodium ions. After that, regeneration takes place.

When choosing a water softening system, one of the main considerations is whether a simplex or duplex system is required. In other words, a duplex system allows for one vessel to regenerate whilst the other vessel can be programmed to remain operational. This avoids any prolonged periods of down time.

Recharging a vessel encompasses eluting the wastewater from the ion-exchange column containing the unwanted calcium and magnesium salts. Typically, this wastewater is discharged to the sewage system.

Recharge typically takes the following steps:


Water is directed through the resin in the opposite direction as normal flow, and the output is sent to a drain for disposal. This 10 minute process flushes out solids, and expands the resin bed.

Brine draw

Water is directed through a jet pump, which pulls salt water from the brine tank, before the water and brine pass through the resin bed in the normal direction, if co-current, or in the reverse direction, if counter-current.


Brine draw stops, but water continues to flow from the inlet to the outlet, gradually flushing the brine out of the resin bed. The flushing water flows slowly for several minutes, then at a faster rate for as long as an hour. At some point, the brine reservoir is refilled with fresh water.


Because bore holes and towns mains water supplies harbour these minerals and elements, water softeners are used to remove hardness from the incoming water supply. These ions would otherwise cause scaling within a water system. Scaling can present itself in many ways.


Below is a list of the most common effects of scaling;

  • Water heaters scaling impedes on their ability to heat water efficiently.
  • Scaling on glassware such as shower screens and glasses is unhygienic and cosmetically unappealing.
  • The scaling on tap outlets and scale build up within water holding tanks can have detrimental effects on systems.


Water softening is a standalone solution in itself. However, it is often used a pre-treatment measure for further finer filtration such as reverse osmosis.


Find Out More

Puretech Water Systems (UK) Ltd specialise in water treatment and process filtration. We work across multiple sectors providing water processing solutions.

Interested in finding out more about reverse osmosis systems?

Find more information here: https://puretechsystems.co.uk/what-is-reverse-osmosis/

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