Water Filter for an Espresso Machine

Question: I am looking for a filter I can connect in-line to my water line to go to an automatic espresso machine. The espresso machine company recommends a filter that will remove all sediment and calcium. Its not clear to me that calcium can be filtered from water. Can you provide any insight or recommendations. This is the espresso machine: DeLonghi Espresso/Cappucino maker I plan to run water line teeing off from the line to my refrigerator ice maker. It is 1/4" compression fitting, but then I must convert it to a 3/4" to the espresso machine. Since my refrigerator...