You can check water hardness by using the indicator test paper included with the machine.

Immerse it in a glass of water for a second and then check the level of hardness - level 1 for soft up to level 4 for hard. Through the menu settings you can then choose the relevant level setting for your water type.

You can download the user instruction from http://www.delonghi.com/en-int/customer-support/user-instruction-manuals