Why are there spots and a white film on my dishes after washing?

Spotting and filming are commonly caused by hard water or high mineral content; using a liquid rinse aid in the final rinse helps eliminate this problem. Low water temperature and insufficient detergent can also contribute, so ensure water entering the dishwasher is at least 120°F (49°C) and use the recommended amount of fresh detergent. To remove existing spots and film, you can occasionally run a white vinegar rinse by placing 2 cups (473 mL) of white vinegar in a glass measuring cup on the bottom rack and running a complete wash cycle without detergent using an air-dry option. (Page 18)