It's an interesting question and one that comes up every time I write about how to use and maintain a dishwasher. For many readers, hand-washing dishes just feels better and is hard to let go of, especially for those who don't use enough dishes to fill the dishwasher more than a couple of times a week.
But isn't low-tech hand-washing just as effective as a high-tech dishwasher? All things considered, the answer might surprise you.
Health and safety
To kill the germs and bacteria on dirty dishes, water must reach a scalding 140 degrees Fahrenheit, according to Kelly Reynolds, Ph.D., a professor of environmental science at the University of Arizona. But if you set your home water heater to that temperature, you'll put family members at risk of scalding themselves when using hot water in tubs, showers and sinks.
Most home water heaters are set to 120 F to avoid scalding, which means getting the tap water hot enough for hand-washing dishes is all but impossible. And even if you could, 140 F is much hotter than your hands could stand for the minimum two minutes that the dishes would need to be exposed to that high temperature. But a dishwasher? No problem. Since the early 1990s, most dishwashers in the U.S. have had built-in heaters to boost water temperatures to 140-145 F.
The advantage of a dishwasher with a booster heater is that you can turn down your water heater thermostat, significantly reducing household water heating costs. Resetting your water heater to 120 F will provide adequate hot water for your household needs.
Hand-washing dishes typically uses a lot more water than a dishwasher. Unless you could get that sink full of dirty dishes hand-washed with soap and rinsed with water in fewer than 2 minutes, it's likely you're using a lot more water than a dishwasher requires, especially if you pre-rinse, wash and then rinse again.
That's because, according to the U.S. Energy Department, a federal standard kicked in for dishwashers resulted in about a 20% reduction in water use. If yours is a highly efficient Energy Star-certified dishwasher, it uses less than 4.25 gallons of water per cycle.
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Not long ago, we remodeled our kitchen. I was without a dishwasher for what seemed like forever, but in reality, it was about a month. That doesn't mean I stopped cooking or we stopped eating at home. I just had to find other ways to get the job done.
Health, safety and economics aside, washing the dishes took so much time — far more time than required with a fully operational dishwasher. It seemed like I was hand-washing all the time and the drying rack was forever full. Even so, there were always dirty dishes in the makeshift sink and clean dishes waiting to be moved from the drying rack to the cupboard.
Not only does my dishwasher save energy and water but it also just makes my life so much easier.
If you don't own a dishwasher
Not everyone has a dishwasher. If that's you, don't panic. You can hand-wash dishes and make sure they are sanitized. The Oregon State University Extension Service says you need to add this one step to the process:
After scrubbing with soap and water and rinsing, soak everything for 5 to 10 minutes in a gallon of hot water — a typical full sink — and 1 tablespoon of chlorine bleach. Don't re-rinse. Instead, allow the dishes to air-dry in a rack or on a drying mat. The bleach will kill any microorganisms that your scouring missed. As everything dries, the bleach will evaporate, leaving your dishes clean and sanitized.
The evidence is clear: A dishwasher is far more efficient than hand-washing dishes. It's faster, safer and cheaper than even the most frugal method of hand-washing.