Dishwasher Water Softening Systems

Even though many of the branded detergents available on the market today claim they provide both the required amount of rinse aid and dishwasher salt, along with  the detergent, this will be insufficient to keep your machine working to its best, especially in a hard water area.

Modern machines are designed to soften the water to give you the best results, in order to do this, you need to top up the salt as and when required by the machine.  This will be depend on the make and model of the machine, plus the frequency of use.


If you check in your manufacturer’s handbook you will see where and how the salt should be added to the machine.  Please be careful to wipe away any excess of salt that may have been spilt during the top up process.  The salt granules may become blocked in the filter, causing rinsing problems.  Your handbook will also identify the indicators that will show up on your machine when it requires more salt, or more rinse aid for that matter.


Dishwashers have built-in water softeners to enable them to exchange hardness ions for sodium ions, by passing water through an exchange resin.  After a given time, this resin needs to be refreshed and the way this happens is the machine calls for more salt.  

The more technical of may need to understand this process in more detail, but others may look away:

Hard water is caused by the calcium and magnesium ions dissolved in the water.  Removing these ions makes the water softer.  The resin mentioned above has a greater affinity for the hardness ions, calcium and magnesium.  An exchange has to take place whereby one part calcium from the water replaces two parts magnesium on the surface of the resin.  The two sodium ions are now part of the water and the the calcium and magnesium ions have been removed from the water and, hey presto, the water is softer.

As stated above, after a certain amount of useage the machine will need to have the dishwasher specific salt replenished, helping to keep the clarity of the finished dishes. The frequency of the need to replace the salt is totally dependent on the hardness of the water in your area, and the number of times you run your dishwasher.




Disclaimer: The information provided has been prepared as a guide only and the steps taken are likely to vary for different appliance models. We strongly recommend using a qualified engineer to undertake major repairs and fault finding.


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