Understanding Your Internal Dishwasher Softener

Some of our commercial dishwashers are available with an internal water softener, designed to protect the machine from limescale damage and improve washing performance. This can be a great option if you have limited space for your installation. However, these types of softeners tend to be smaller traditional external units, so only offer protection up to a certain water hardness level.

Depending on where you live in the United Kingdom, you may sometimes find that an internal softener can’t offer full protection from limescale build-up or may require very frequent regeneration in order to do so. Particularly in exceptionally hard water areas such as the South East of England.

Maximum Water Hardness

All manufacturers offer different recommendations, but most commercial dishwashers with an internal softener are rated to a maximum of:

  • 35°f (French degrees)
  • 19.7°dH (German degrees)
  • ≈ 350 ppm (as CaCO₃)

These are simply different ways of expressing the same hardness level. In practical terms an internal softener can usually effectively treat water up to approximately 350 ppm.

Adjusting Regeneration Cycle Frequency

Machines fitted with an internal softener require the frequency at which the automatic softener regeneration cycle runs to be adjusted depending on the incoming water quality. The exact manufacturer’s recommendations will vary slightly between makes & models, but as a general guide we recommend:

Water Hardness °f

Water Hardness °dH

Regeneration Frequency

0-10

0-5

No softener required

11-15

5-8

Every 35 washes

16-19

8-10

Every 30 washes

20-23

10-12

Every 26 washes

24-27

12-15

Every 22 washes

28-30

15-17

Every 20 washes

31-35

17-19

Every 16 washes

35+

19+

Use an external softener

We always recommend that you check the user manual for your specific model to find the correct regeneration settings when installing and commisioning. 


Why An External Softener May Still Be Recommended

Even if you choose a dishwasher with an internal softener, it is often still recommended to use an external softener as these units have a much larger capacity and therefore offer better protection in very hard water areas. We always recommend an external softener if:

  • Water hardness is around 350ppm or above
  • You frequently or intensively use the machine
  • Automatic regeneration would be required to run so frequently that general use would prevent it from successfully completing or mean it's frequently interrupted. 
  • The frequency of the automatic regeneration cycle would mean the machine must be constantly topped up with salt (for example every day).


Checking Your Water Quality

There are several easy ways to find out what quality of water you have in your area. This helps you to make an informed decision as to whether a model with an internal softener is suitable for your situation:

  1. Check online by postcode
    Most regional water suppliers publish water quality test data online. You can visit your local water boards website, enter your postcode and view your areas hardness rating.

  2. Use a water hardness test kit.
    These are inexpensive and widely available from most hardware stores. Options include dip test strips (quick and simple) or drop-count titration kits (more precise). Simply follow the instructions and compare the colour result to the included chart.