Ask Real Simple: Is Hand Washing Dishes as Effective as a Dishwasher?
Real Simple answers your questions.
Q. Does hand washing dishes get them as clean as the dishwasher does?
La Cañada Flintridge, California
A. Not completely. To kill most of the bacteria on a dirty dish, water must reach a scalding 140 degrees Fahrenheit, says Kelly Reynolds, an associate professor of environmental health sciences at the University of Arizona, in Tucson. That temperature is easily reached in a dishwasher, but in a sink, it’s nearly impossible. Hot-water heaters are typically set at 120 degrees to prevent burns, and most people can’t stand to keep their hands in a stream of water that hot for more than a few minutes. So when it comes to washing dishes, high-tech beats low.
Should you worry, then, about Grandma’s Wedgwood, which is too delicate for the dishwasher—or your grandma who doesn’t own a dishwasher? Rest assured: Hand washing does an acceptable job. But if you want your dishes sanitized, according to the Oregon State University Extension Service, you should add one step to the process: After scrubbing with soap and water, soak everything for 5 to 10 minutes in 1 gallon of hot water and 1 tablespoon of chlorine bleach (the ratio works for a sinkful of dishes). The bleach will kill any microorganisms that scouring failed to expunge. (This is a good idea if someone in the house is sick.) When everything dries, the bleach will evaporate, leaving your dishware so clean that you can, well, eat off of it.