Iron
If there is iron in the water entering the dishwasher, a brown or orange film may deposit on the dishes, leaving them looking dirty or dingy. One way to determine if there is iron in the water is to run water from a faucet and examine it closely. If it has a brown, yellow or reddish tinge, there is likely iron present. A more accurate method is through the use of a water testing kit, which can be purchased at many hardware stores.
Water Filter
Installing a household water filter can help resolve issues with iron as well as hard water, which may contribute to brown stains on dishes. Different types of filters will remove iron, including sediment and carbon filters, which are best for red water iron. Clear water iron can be treated with a manganese greensand filter, often called an "iron" filter. Most filter types can be purchased at a hardware store and connected to the household water supply.
Water Softener
Another treatment to remove iron and improve household hard water is the installation of a water softener in connection to the home water supply. A water softener will remove hardness caused by minerals, including iron, magnesium and calcium. Note that iron may cause the water softener to become blocked, so frequent cleaning or replacement may be necessary.
Cleaning the Dishwasher
A dishwasher with a brown stain or with stained dishes must be cleaned thoroughly. Add 3 tsp. of citric acid crystals to the detergent container of the dishwasher, and run a normal wash cycle. Do not add detergent with the citric acid crystals. Once that cycle is complete, run another normal wash cycle with automatic dishwasher detergent.