To minimize hard water buildup, decalcify the dishwasher regularly with white vinegar. Pour 2 cups of vinegar in a drinking glass, or place 1 cup of vinegar in two separate glasses, and put the glass or glasses in an otherwise empty dishwasher. Run the dishwasher on the normal or regular cycle without detergent. Do not use the sanitize or high-heat cycle. After running a normal cycle, allow the dishwasher door to remain open until the vinegar smell dissipates.
To further reduce the effects of hard water, use a dishwater additive that is specifically designed for hard water. For instance, detergent boosters that remove mineral deposits on dishes also remove mineral deposits inside the dishwater.
Another option is to install a whole-house water softener. Water softeners typically filter the minerals out of the water before the water enters the home, eliminating hard water buildup in appliances. Choose a water filter doesn't remove fluoride, as fluoride is essential for healthy teeth.
Alternately, install a point-of-use water filter that connects directly to the dishwasher's water supply lines. Point-of-use filtration systems are typically installed under the kitchen sink. Change the filter on the system as recommended in the owner's manual to ensure the filtration system works properly.