If you are on a Municipal or City Water System, I would venture to say that its not Calcium, but Lime that is going through your lines.
Most Water Systems inject lime into the water to "coat" the pipes, because most systems have old "lead pipes" that have been in the system if they are over fifty years or older. So, they need to have these coated, so that there is no leaching off of lead, to create lead poisoning to families. Thus the lime in suspension.
A whole house water filter, either string or carbon filter will take out the lime that is in suspension, and save your pipes and faucets from harm. I know, I have two of them in line. One coming into the main after my water meter,and another one coming up for the main sink and ice maker.
You will find that in one month or less, the main one will be "yellow" with lime and "gunky", or slimy from the film it puts on the string filter. It will take out calcium also, in suspension.
String filters take out .05 microns and carbon takes out .02 microns, and if your Water System loads lime heavily, or you have a line break near your home, you will be replacing filters about every two weeks. (The filters come two to a pack for about 7 bucks in my area). I can get away with one change a month, usually, but, I have changed them as many times as three times a month, when I didnt know they were flushing firehydrants!
But, in the long run, its cheaper with a whole house water filter, than the other one... Filter is probably 40 bucks or less, and you have to remember to take the pressure off, when changing the filters, by opening a faucet after shutting off the entire house, or valve before the filter, so there is no pressure and the wrench is easier to take it off with...
Just my two cents worth...