Here's Why Your Dishwasher Is Leaving White Residue—and What You Can Do About It

A dishwasher is one of the all-time best kitchen inventions. If you hate to wash dishes by hand, a dishwasher makes clean up so much easier. And according to the Environmental Protection Agency (EPA), compared to washing dishes by hand, an ENERGY STAR qualified dishwasher can save you almost 10 days a year of your precious time, cut your water and energy costs by more than $40 a year, and also save you close to 5,000 gallons of water.

However, when your dishwasher doesn’t clean as well, a lot of the benefits go down the drain—and you could be left with an annoying white residue on your dishes. In order to fix the problem, you have to know the cause, so here are some of the reasons why your why your dishwasher is leaving white residue, and some solutions to make your dishes sparkling clean.

Hard Water

Fortunately, hard water doesn’t cause health problems. However, it can negatively affect the performance of detergent in your dishwasher. “There are high levels of minerals that are contained in hard water, normally calcium and magnesium,” explains Glenn Lewis, president of Mr. Appliance, a Neighborly company. When the water in the dishwasher evaporates, he explains, it will leave these minerals behind, and they’ll show up as a white residue. Lewis recommends using a water softener or rinse aid to combat the mineral buildup on dishes. “You should also properly and routinely clean your dishwasher to help combat this as well,” Lewis says.

Hard water is actually quite common and is found in cities and towns across the country. According to Alessandro Gazzo at Emily’s Maids in Dallas, Texas, his city has hard water, and he says those residents—as well as anyone living in a place with hard water—are likely to see mineral deposits in their sinks and showers as well, as a result of the mineral deposit buildup. To solve for the mineral deposits in your dishwasher, Gazzo recommends putting a glass of vinegar in the top rack and running your cycles as usual. And if vinegar doesn’t work, he recommends running a normal cycle using 3 tablespoons of citric acid in the detergent cup.

Detergent

Although detergent is used to remove food and grime, a build-up of detergent can also end up leaving white residue—especially if hard water is an issue. “Hard water contains elevated levels of minerals like calcium and magnesium, which can react with soap to form scum,” explains Kenneth Bass, virtual appliance expert at Frontdoor.

Also, if you use too much—or too little—detergent, Lewis says it may result in a buildup of residue. “Excessive detergent doesn’t rinse off and can leave a white film around the dish,” he says.

In addition, it’s possible that you’re using the wrong type of detergent. According to Gazzo, cheap liquid detergent can cause a white—or even a black—residue, especially when combined with hard water. Gazzo recommends using a good quality dishwasher powder, and also suggests using less detergent. “Dishwasher detergent, laundry soap, and toothpaste have one thing in common: We usually use way too much,” he says. Gazzo also recommends running a test with just a half of the usual amount of detergent to see if your dishes come out clean.

Lewis agrees that a high-quality detergent can help to prevent this buildup—and stresses that it's important to use the correct amount. “If you are still seeing this issue after using the correct amount of detergent, it may be time to switch to another brand,” he says. Also, be sure to follow the manufacturer’s recommendations regarding detergent usage.

To remove white residue caused by detergent, Bass, like Gazzo, recommends running an empty dishwasher cycle with vinegar. “Pour white vinegar into the bottom of the dishwasher or put a coffee cup full of vinegar on the top rack and run a cycle without adding soap, as this helps dissolve soap scum,” he says.

Bass also recommends cleaning the dishwasher filter. “Regularly remove and clean the filter to prevent debris and soap residue from clogging it,” he says. Bass also advises running a cycle on the longest, hottest setting (without soap) to clean the machine of soap build up.

“A capful of vegetable oil can be added straight to the water in the bottom of the machine to help break down and remove excess soap,” Bass says. “Add the oil after the machine makes its first rinse and drain in the cycle. Then, open the door and pour the oil straight into the bottom of the tub; shut the door and let the machine finish the cycle.”

Water Temperature  

Here’s another tip: Check to see if your dishwasher is heating correctly. “It’s important that your dishwasher has hot water to ‘melt’ every residue of grease and minerals from water,” Gazzo explains. Bass agrees that you should check the water temperature to see if this is the root of your residue issue. “Ensure your water heater is set to at least 120 F (49 C) for effective cleaning,” he says.

Other Solutions

To curb the issue of white residue, Bass also recommends using rinse aid, or a similar additive rinsing liquid when running your dishwasher—and be sure to refill it as needed. “This will improve drying performance by reducing water spots and enhancing water sheeting,” he explains.

Another thing to try: Adjust the dispenser setting. Bass recommends consulting your dishwasher manual to set the correct level for your water hardness.

It’s important to determine what’s causing your problem. According to Lewis, a mineral buildup can cause issues with the spray arms, valves, and pumps in your dishwasher. “Be sure you are cleaning and maintaining your dishwasher based on the manufacturer's guidelines,” he says. And if the issues continue, Lewis recommends calling in a professional to look into the problem.