Your water is hard when it is full in calcium, magnesium and minerals. The water is soft when it contains a few of the mentioned components. When the hard water heats up, mineral deposits are formed on your continents surfaces, this is called “limestone”. This content of mineral salts depends on the geologic nature of the soil crossed by your water. The hardness of the water is expressed in French degree (°F or TH). One hardness degree in French corresponds to 4 milligrams of calcium per water litre. A water is : - Soft : < 7 TH - Medium soft : from 7 to 21 TH - Hard : from 21 to 28 TH - Very hard : > 28 TH Each country expresses the water hardness in degrees, which does not correspond to the same quantity of salt. Barriclean prescribes to install an anti-scaling system on your installation if the water hardness is above 21°F. If you wish to know the hardness of your water, you can contact the company in charge of the water supply (coordinates on your invoice for water). You can also achieve your measurements thanks to test-strips, or by contacting us. * Option : for very hard water, we recommand to use our Decarbonator Kit, which we fix outside the device.