What does the sanitize button on a dishwasher actually do?

We’ve been getting a lot of questions lately about the sanitize cycle on dishwashers. People want to know if it can kill viruses, like COVID-19, and what to do when you don't have one.

According to the Centers for Disease Control and Prevention, there is no definitive evidence of a certain temperature that kills the virus; however, the flu dies at temperatures of 167°F and above. Sanitize cycles on high-end dishwashers reach temperatures upwards of 170°F. To put that in perspective, the Normal cycle on the Whirlpool WDT730PAHZ, for example, gets up to around 140°F—the temperature at which most food-borne bacteria dies.

That hot water, coupled with detergent, is likely enough to fully clean any dishes, but here's more information about the sanitize cycles and whether you should start using them in your day-to-day.

What does "sanitize" mean?

For something to be considered sanitizing, the Environmental Protection Agency looks for removal of 99.99% of bacteria. The National Sanitation Foundation, a product testing company, awards certain appliances with certifications, like the NSF/ANSI Standard 184, which makes sure that a dishwasher can reach at least 150°F during the final rinse. That's the temperature that kills germs like E. coli and Legionella.

Both of these definitions are important. You can kill 99.99% of bacteria with chemicals like alcohol or bleach, or with heat. If a dishwasher can truly sanitize, we think it should be able to do so without detergent.

How does a sanitize cycle work?

On most dishwashers, there is either a separate Sanitize wash cycle or a special setting. When you select this cycle, the dishwasher takes in hot water and heats it up even further. An electrical heating element does the brunt of the work of getting the water to the required high temperature.

What are the benefits of using a sanitizing cycle?

To get a sanitize cycle, especially one that’s certified, you have to pay a premium for a dishwasher—between $500 and $1,200 is not uncommon. While the initial cost may be hard to swallow, there are multiple long-term benefits.

First and foremost, a proper sanitize cycle will help prevent illness. It can kill bacteria on utensils and plates, but also Legos and plastic toys as well. It’s easier than hand-washing, and more effective because the water can get hotter than your hands can stand.

And while, generally, you shouldn’t put cutting boards into the dishwasher, dishwasher-safe cutting boards that have been used to cook meat and poultry can benefit from the increased temperature.

A proper sanitize cycle is also indicative of great stain removal performance. Our lab testing shows that stains, like burnt on cheese and spinach, can be loosened and removed by high temperatures.