The water in my area is so full of calcium that we have to use a dishwasher additive every load to avoid white film on everything. If we don't, the coating on inside the coffee cups attracts coffee stains. The coffee stains the calcium deposits, actually, so it is a big ugly mess.
The additive I use is called Lemi-shine. It is mostly citric acid. Vinegar also works, if you have calcium deposits in a big pot or tea pot. I could write an essay on Lemi-shine. I love it and sort of panic if I can't find it at Walmart, lol!