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Dishwasher Discoloration

Submitted by Lorene Bartos, UNL Extension Educator

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Does your dishwasher need attention? Discoloration of the interior of the dishwasher is a problem that occurs occasionally. If this problem occurs, it may be caused by several different reasons.

Iron or manganese in the water supply can cause brown, red or black stains on dishes or the dishwasher interior. This discoloration can be removed by using a rust remover. Fill both detergent cups with the rust remover. Set the controls and run a normal wash cycle. Follow with an additional rinse cycle. Do NOT use a rust remover with dishwashing detergent.

Foods can also discolor the tub interior. To reduce this problem assure the inlet water is a minimum of 120 degrees F and the water heating options are being use. IF the dishwasher is a non-water heating model, the inlet water should be 140 degrees F for optimum results. Also, increase the amount of detergent being used. More detergent will help to keep food soils suspended. Less contact with the dishwasher tub will help prevent transfer of color from food soils on the tub. To remove the discoloration, fill both cups with a citric acid product such as Tang or Fruit Fresh. Run a normal cycle. Follow with another cycle and dishwasher detergent.

A lime film or deposit may build up on the interior if there is a high calcium level in the water supply. Use one of the following procedures to remove this type of deposit.

* Use a damp cloth and a mild scouring powder.

* Initiate the rinse and hold cycle (with an empty dishwasher). During the fill, open the door and add ½ cup white vinegar to the water. Allow the cycle to complete (without detergent). Follow with a normal cycle with detergent.

* Fill both detergent cups with rust remove. Set the controls to complete the normal wash and rinse cycles. Follow with a shorter wash cycle with detergent.

* Fill both detergent cups with baking soda. Select a short wash cycle. After the water has circulated for about 5 minutes, unlatch the door to stop the dishwasher and let it stand overnight. In the morning, latch the door to restart the dishwasher and allow the cycle to complete.

To save energy when using the dishwasher always wash a full load. Use the no heat dry selection. Use the short wash cycle for lightly soiled dishes.

Remember to read the owner/operator manual of the dishwasher. Do not use any products that should not be used in your particular model.


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(This resource was updated August 2008 and appeared in the Lincoln Journal Star Newspaper Sunday edition. For information on reproducing this article or using any photographs or graphics, read the Terms of Use statement)

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