Soft Water for a better way of life

How Water Softeners Work

The best way to learn about how water softeners work is to book one of our demonstrations, you’ll be able to see softened water in action from your own tap.

In brief, water softeners are designed to remove calcium and magnesium (the cause of scale and scum) from hard water. They are intended to treat the whole house, so are installed where the water supply enters the premises.

Ion Exchange

Water softening happens through a process called ion exchange, which uses an ion exchange resin. The resin comprises of tiny polymeric beads which are specially formulated so that they can be charged with certain ions. Calcium and magnesium, the causes of scale and scum from hard water, are referred to as ions, and as water passes through the resin, the calcium and magnesium ions swap places with the sodium ions on the resin. Sodium salts, unlike calcium and magnesium, are highly soluble so sodium does not cause scale or scum. When all the sodium ions have been exchanged for calcium or magnesium, the resin must be regenerated by recharging it with sodium ions. This is done by flushing the resin with salt solution (brine).

In the diagrams below

Fig 1.  shows the brine tank containing salt, the pressure vessel containing the resin and the control valve.
Fig 2. shows the Service Cycle - hard water enters the control valve where it is sent down through the resin bed where the hardness minerals are removed.  The soft water then travels up through a tube and out to feed the house.
Fig 3. shows the Regeneration Cycle - initiated by the control valve, salty water (brine) is sucked up through the resin where it collects the hardness minerals and flushes them out down the drain.  Once completed, the resin bed is then flushed through with clean soft water to ensure all of the brine is removed from the resin.


                                   Fig 1.                                                           Fig 2.                                                          Fig 3.       

Different Types of Water Softener

Although all water softeners work on the same principle, as described above, they differ in many ways:

Control Valve

There are two different types of control valve, timer controlled and meter controlled:

    • Timer controlled valves have a timer that initiates the regeneration at preset intervals based on expected water usage. Usually every two or three days (regardless of actual water usage). Some softeners have a more complex control system and try to predict more accurately water usage but are fiddly to program and still fall short of only regenerating when required. If the softener does not regenerate before the resin is exhausted, then hard water will enter your plumbing system once again - this can take several days to dissipate once regeneration has occurred.
    • Meter controlled valves meter the service water so that they can decide more accurately when they need to regenerate. This means that if the homeowner goes on holiday and doesn’t use water, the softener will know and postpone the regeneration saving salt and water. There are two types of meter: turbine and displacement. The turbine type can suffer from inaccuracies introduced by low flow rates. It also introduces a larger flow restriction and therefore requires different models for different household pressure systems. The displacement type, however, overcomes these limitations by accurately measuring every drop of water that passes through the meter. In addition, it is much larger and therefore presents a much reduced restriction providing a higher flow rate.  Only the Dualflo Water Softener uses a patented displacement meter designed specifically for the UK market.


Water softeners have one or two cylinders:

  • One cylinder are most common.  Because there is only one cylinder this type of softener can only operate in one of two modes, either service cycle (where it is giving softened water) or regeneration cycle (where it is cleaning itself). It can't do both things at the same time.
  • Two cylinders enable better efficiency because each vessel can be completely exhausted before the second vessel comes into service - there's always a back up and softened water is always available, even during regeneration. Where all other two cylinder softeners provide softened water through one cylinder, uniquely, once the regeneration process is complete, the Dualflo puts both cylinders in to service mode thereby further reducing the restriction and increasing the flow rate.

    Hard water pumped into your home passes through a bed of resin crystal beads in the unit which capture the lime scale and minerals by an ionising process. When the beads become exhausted, they need to be regenerated by flushing through a salt water solution. Because of its technologically advanced design and unique features, Dualflo has more efficient operation than conventional models, which makes it the best performer on the market.


    • Electric – most softeners use mains electricity to drive the control valve. Disadvantages of this system include the necessary to provide a local power socket which may increase installation costs and additional costs running costs.
    • Non-Electric – There is no programming and should there be a power cut, there’s no need to reset anything.  The Dualflo is non-electric.


There are two types of salt systems:

  • Bags - Tablet salt comes in 25kg bags which are heavy and awkward to deal with.
  • Block Salt – makes the whole process a lot easier. The salt is pressed into 4kg blocks and they’re much easier for the customer to carry and load. The Dualflo uses block salt.


Apart from adding a salt block from time to time, the Dualflo  is completly maintenance free.


The Dualflo is small & simple.  Even adding Block Salt is simplicity itself...a matter of seconds. The diagram shows how the clever sliding lid design lets a new block tip in without any extra height being required. The amazing Dualflo Block Salt Softener fits comfortably under a standard sink unit. Alternatively the Dualflo can be installed outside with one of our insulated outside cabinets.

Still Confused?  Everybody is!  There are many different products on the market - you can have softeners with timer control or meter control; single cylinder or dual cylinder; tablet salt or block salt; electric or non-electric......... we have taken out the hard work and thoroughly researched the market to find, what we believe, to be the best product on the market.

In a Nutshell:

Ion Exchange Hard Water Softeners are effective in:

    • Preventing scale in the hot water system and around taps
    • Removing existing scale
    • Reducing boiler fuel cost and heating system maintenance costs
    • Preventing soap scum, which is evident around the bath and sink
    • Reducing soap and detergent costs.
    • Improving the texture of laundry by preventing detergent scum deposits within the fibres of clothes, bedding, etc.

The Dualflo  Softener is the market leader because it is:

  • Non- electric
  • Meter controlled
  • Uses a patented displacement meter
  • Dual cylinder
  • Uses both cylinders for service water
  • Soft water always on line
  • Block salt
  • Maintenance free
  • Compact size
  • Efficient in use of water and salt during regeneration
  • Designed and Made in the UK specifically for UK homes

Click here if you would like a FREE, ON OBLIGATION demonstration