If you have hard water, follow these guidelines: Use the maximum recommended amount of dishwasher detergent (not dish soap) recommended in your Use and Care Manual. Use only the correct amount of dishwasher detergent according to your water hardness (check your Use and Care Manual for details) and the wash program selected. Fill the dispenser only when you are ready to start the dishwasher. Do not use old or caked detergent. Store dishwasher detergent in a dry place and in a closed container. Change your dishwasher detergent if results are still poor. Make sure the rinse aid dispenser is full. Make sure the dishwasher is loaded according to the instructions in your Use and Care Manual. Do not overload. To remove hard water spots, try a vinegar rinse: Wash and rinse the load as usual. Remove all metal items from the dishwasher. Do not add detergent. Pour 2 cups of vinegar into a bowl and set it on the bottom rack. Run the dishes through an entire wash program. If the vinegar rinse does not work, repeat the process substituting 1/4 cup of citric acid crystals (available at most drug stores) for the vinegar.
If your water hardness exceeds 3gpg, you should use a rinse agent with citric acid (acid rinse agent). In hard water areas, both the dishes and the machine can develop a white or gray film after a while. This can be removed by replacing the pre-wash detergent with two tablespoons of citric acid.
Wiping metal items with a damp cloth should remove spots. For sterling and silver plated flatware, rub with a towel, or use a good cream silver polish. If spotting and filming persists, you may need a home water softener.
Note: Different brands of dishwasher detergent have different amounts of phosphorous for softening water. In some areas with hard water, you may need to use more detergent if it has less than an 8.7% phosphorous content or change to a detergent brand with more phosphorus.
If you have soft water, be careful not to use too much rinse aid, this can create spotting and filming. Adjust rinse aid dispenser according to the instructions in your Use and Care Manual.
If you have very soft water and still experience streaking when the dispenser is set to position 1, you can dilute the rinse agent with water before pouring it into the dispenser to get acceptable results.
Other steps to avoid spotting and filming include: Run the garbage disposal to eliminate food and obstructions in the sink, prior to starting the dishwasher. Make sure the sink drains properly. Make sure the spray can reach all soiled surfaces and that both spray arms rotate freely. Items should not obstruct movement of the spray arms. If necessary, clear any obstructions and clear spray arm holes with a pointed object and rinse under water. Check the hot water supply temperature. Minimum recommended incoming temperature to the dishwasher is 120°F. Make sure the water valve is fully open and that the water pressure is between 20 and 120psi. The flow rate is a minimum of 1.0 gpm. In addition, be sure to check the strainer and clean if necessary. Also make sure items are not nested during the wash or rinse cycles.