Water Softeners: single and twin tank systems

Water Softeners: single and twin tank systems

Is less really more!

Amongst the huge variety of ion exchange water softeners available in the UK there is a one question which is asked again and again, ‘which water softener is better, a single tank system or a twin tank system?’

For those people not familiar with the design of water softeners.  All ion exchange water softeners use resin beads to provide an exchange process which, as the hard water passes through the beads, takes out the calcium and magnesium from the hard water and replaces it with trouble-free sodium ions.   Some water softener systems will use a single resin vessel for this process and some use twin tank resin vessels.  All water softeners have a self cleaning process called regeneration or recharge.  This is when the water softener will wash the calcium and magenisium collected by the resin beads to drain, and recharge the resin ready to create more soft water.

As far as deciding which water softener is better, a single or a twin tank, is unusually for water softeners, not too difficult to answer; it’s a matter of performance and efficiency.

Water softeners which use twin tank systems by their very nature normally have two low capacity resin vessels which produce around 350-400 litres of soft water before they need to regenerate.  In comparison an EcoWater ESM11+ single tank system produces 2,400 litres of soft water (at 300 ppm hard water) before it needs to regenerate.

It is true that a single tank system will use more salt and water per regeneration than its twin tank counterpart, however this is counteracted by the fact that a twin tank system will regenerate much more often and therefore actually use more salt and water per 1,000 litres of soft water produced.

Costs per 1,000 ltrs of Soft Water

 

 

As you can see the twin tank systems use much more salt and water than the EcoWater ESM11+, which is not only bad for your pocket but bad for the planet.

There are also some technical issues with water softener twin tank systems which need to be considered.

As mentioned earlier twin tank systems are normally made up of two low capacity resin vessels and when one tank starts a regeneration this means a single vessel is supplying all of the water for the property and as a result you can experience flow rate issues (pressure drop-off). This will not happen with a single tank system such as the EcoWater ESM11+ as it predicts regeneration based upon your usage and will regenerate, if necessary, at 2:00am when there is no requirement for water.

Two tanks also means twice the amount of parts therefore reliability is a concern. This can be experienced as drop off in performance, water which is not fully softened or worst case scenario breakdown resulting in costly repair bills.

With the additional number of parts as well as the greater number of regenerations (more than four times as often in the example above) taken into consideration this means that the unit is working much harder and therefore life expectancy is compromised.

Twin tank systems are normally seen as advantagous because they provide 24/7 soft water and because of their size.  However, most homes are not using water 24 hours a day, and therefore, this requirement is not normally necessary.  The design can be compact and will fit into spaces that are too small for conventional water softeners but as you can see this feature comes at a cost, a significant cost over the life of a water softener.

Therefore if you have enough space then there is only one decision, single tank water softener every  time.

View some of our frequently asked questions about the water softener range