If you also notice a problem with getting soap to lather or a cloudiness in the water, you most definitely have a hard water problem. That basically refers to having an excess amount of minerals in the water and that's directly related to where your water comes from. So if you happen to have a stone quarry that your water comes from you're going to have more hard water in it. It can occur with both well water as well as city water.
There are a couple of things that you can do to eliminate hard water. First of all, with respect to the dishwasher, there's such a thing known as a rinsing agent and the most common one out there is a product called Jet-Dry.
Most dishwashers have the rinsing agent dispenser built in. The product leaves a coating on your glasses that makes the water evaporate quickly and lets the water run off.
You also might want to think about putting in a system to treat your hard water. Now, typically that's done with salt-based treatments, but it takes some time and some expense for the plumbing to be installed. There's another system out there that we like called EasyWater. EasyWater uses an electronic technology, instead of salt or chemicals, to make sure that the minerals don't stick to plumbing, fixtures or your dishes.
What's great about it is that it doesn't require any plumbing to install. It's about the size of a college textbook and you simply put this near your main water valve to eliminate hard water stains. There is a wire that you wrap around the main water supply pipe and essentially what happens is the minerals in hard water their electrostatic charge, which is what makes them stick to the faucets, the glasses, and everything else.