My Dishwasher Leaves a Film

Hard Water

One of the most common reasons for film left on dishes at the end of a washing is hard water used in the washing process. Hard water has an excessive amount of minerals such as calcium and magnesium. As hot water from the dishwasher flows over the dishes during a normal cycle, these minerals separate from the water and deposit on the items in the wash. This can result in either small spots or large patches of deposited mineral. Problems resulting from hard water are solved in the dishwasher either by adding a water softener to the dishwashing detergent during washing or by adding a water softener to the house plumbing system.

Another cause for white film is the residue left behind from detergent that isn't coalescing properly with the wash water. This process, referred to in the industry as "sudsing," requires water at a temperature of at least 125 degrees Fahrenheit. If the water is too cold, the detergent will stick to the dishes and cups, creating a white film. Too hot is also bad: Water temperatures over 140 degrees Fahrenheit can cause "etching," which causes a thick layer of white film on glasses. Unlike a lack of sudsing, etching is permanent filming on the glass and cannot be washed off or removed. Running glasses and dishes on a lighter setting, such as "Power Saver" instead of "Power Scrub" or "Pots and Pans" will reduce the amount of heat used during a wash.

Different types of dish detergent affect the wash in different ways. Phosphate-free dishwashing detergents, for example, are safer for the environment but the lack of harsh chemicals can reduce washing performance, leading to spots and film in the wash. Government regulations prevent detergent manufacturers from putting phosphates in dish cleaner, but rinsing agents that use citric acids will minimize film if added to the wash.

If the film on glasses and dishes is a dirty one, it may stem from a lack of water pressure during the wash. Low water pressure will cause the soapy water to spread out dirt but not have the force to blast it free from the glasses or dishes. Avoid using water for other purposes, such as bathing or washing clothes, during a dishwasher cycle to increase water pressure.