https://www.naturewater.eu
Item 63924
Page 23
01 2024-1
Water hardness and testing
Total water hardness
The total water hardness results from the total content of calcium and magnesium ions in the water,
including the carbonate hardness (i.e., the calcium and magnesium ions that can be excreted as car-
bonate by heating, therefore also referred to as temporary hardness) and the non-carbonate hardness
(i.e., the proportion of calcium and magnesium ions that can no longer be excreted after heating, there-
fore also referred to as permanent hardness).
Testing the raw water hardness
Immerse the reaction zone of the hardness-test paper in the liquid to be tested for 2 s. Remove and
wipe off the excess water droplets. After 15 s, compare the colour with the colour chart. The colour is
close to the concentration value. Make a note of the measured value for later use.
The hardness expressed by the CaCO
₃
content can be roughly divided into
Degree of hardness
Description
0–75
Very soft water
75–150
Soft water
150–300
Middle-hard water
300–450
Hard water
450–700
Very hard water
700–1000
Super-hard water
>
1000
Extra-hard water
