Auxiliary · Water

Water Hardness Converter

Enter a total-hardness value in the unit shown by your report or test. The page converts the unit; it does not assess water safety, flavour or equipment suitability.

Tool

Hardness value

Unit

How It Works

Total hardness is commonly expressed as calcium-carbonate equivalent. Different reports use different units, so this converter normalises them through ppm as CaCO3: one German degree is 17.848 ppm, one French degree is 10 ppm, one grain per US gallon is 17.118 ppm, and one millimole per litre as CaCO3 is 100.09 ppm.

The conversion says nothing about alkalinity, total dissolved solids, microbial safety, individual ions or equipment instructions. Those are separate questions that require the underlying report, a suitable test or the equipment manufacturer’s guidance.

Step-by-Step Usage Guide

Locate the total-hardness value and unit in a water report or relevant test result.
Enter the number and choose the matching unit.
Use the converted value to compare reports that use different units.
Check alkalinity, TDS, safety and machine care separately; this tool does not calculate them.
Follow local water guidance and equipment-maker instructions before changing a water supply.

Frequently Asked Questions

Is hardness the same as TDS?+

No. They are distinct measurements. A total-hardness conversion cannot substitute for a TDS value.

What about alkalinity?+

Alkalinity is a separate measurement and is not derived by this converter.

Can I brew with distilled water?+

This converter does not make a recommendation about any water supply. Follow your recipe, relevant local guidance and equipment instructions.

Does hard water damage my equipment?+

Equipment requirements are model-specific. Use the manufacturer’s water and maintenance guidance rather than a generic hardness threshold.

Applicable Scenarios

Relevant to anyone whose coffee tastes different at home than at a café despite identical beans and recipe, to espresso machine owners planning a descaling schedule, and to enthusiasts mixing their own brewing water from concentrates. It is also handy when travelling, since regional water hardness varies enormously.