Simplest way to take a little bottle with a line marked on it which you fill to the line with water, add a drop of soap, and shake to look for suds. More drops of soap - more degrees of hardness. Otherwise, hardness can commonly measured by colorimetric titration with an EDTA solution. A titration involves adding indicator and then titrant solution in small increments to a water sample until the sample changes color. You can titrate a sample for total hardness using a burette or use a water hardness test kit.

J. C. Tarafdar Thank you for your answer.

Measuring water hardness is not complicated and the methods used are simple and cheap. What type of method to use depends on the type of treatment process where hardness is being monitored. From a health point of view, hard water is good. Hardness, on the other hand, is a problem in industrial waters. Water hardness can be measured by titration with EDTA solution or you can use for fast measurement drop count test kits or strip tests.