Converting water hardness
In the Netherlands, we usually express water hardness in German degrees (°D). In addition to German degrees, countries such as Belgium and England use other units to measure water hardness. In Belgium, French degrees are used, and in England, English degrees are used. For example, we refer to water as ‘hard’ when it contains a lot of limescale and the water hardness exceeds 12 °dH.
Water can be divided into five categories.
Calculate your water hardness yourself
It is very easy to measure the water hardness of your tap water using a water hardness test. With this test, you can find out the hardness of your tap water in a matter of seconds. The test is available from our online shop.
When the calcium level is high (2.4 dH and above), this can have an impact on the household. The water is then harder, which increases the risk of limescale build-up in places such as the shower or the washing machine. Reducing the calcium level has many benefits.
Converting German, French and English degrees
It is important to know that 1 German degree is equal to 10 milligrams calcium oxide (CaO) per litre of water. One French degree, on the other hand, consists of 10 milligrams calcium carbonate (CaCO3) per litre of water. In addition to the French and German degrees, other units are used to indicate water hardness:
Ppm: ppm stands for parts per million and is a ratio. Just as 1 per cent corresponds to one hundredth of the total and 1 per mille corresponds to one thousandth, 1 ppm corresponds to one millionth of the total. A water hardness of 1 ppm occurs when 1 milligram calcium carbonate (CaCO3) has been dissolved in 1 litre of water.
mmol/l: A mole is the chemical unit for a quantity of substance. A millimole is one thousandth of a mole. 1 mmol of lime per litre of water is equal to 5.6 °dH. Water supply companies are required not to soften drinking water by more than 1 mmol/l.
Would you like to convert the hardness of your water to a different unit? You can do so using this table:
Have you made a decision yet?
Why not request a free, no-obligation quote?
Example: Converting German degrees
Example: The water hardness in Lelystad is around 5°dH. To work out what this equates to in another unit, we need to multiply the German degree by the conversion factors below:
The concentration in the other units can be calculated as follows:
- 5°dH multiplied by 1.78 is the French degree
- 5°dH multiplied by 1.253 is the English degree
- 5°dH multiplied by 17.8 equals ppm
- 5°dH multiplied by 0.178 equals mmol/l
The converted units are as follows:
Are water softeners right for you?
Stop limescale build-up, save on cleaning products and energy, and extend the life of your appliances!
Further information
Are you wondering how you can reduce the hardness of your tap water? Then take a look at our range of models water softeners.
Do you have any questions?
We’re here to answer any questions you may have!
Have you made a decision yet?
Why not request a free, no-obligation quote?
Running costs
Compare
Overview of water softeners
Placement
Water hardness
Facts and myths
