Dishwasher vs hand washing: which is the most eco-friendly?

Probably no one really enjoys washing dishes. That’s one reason we have dishwashers, but probably no one enjoys loading them. If we’re going to use dishes, we have to wash them. So what’s the best and most eco-friendly way to do it: use the dishwasher or hand wash?

Hint: most experts give the nod to dishwashers, but you can’t avoid hand washing entirely.

Our question breaks down into several other questions:

• Which method uses the least water?
• Which method is the most sanitary?
• What can and cannot go into a dishwasher?
• What is the best and most eco-friendly way to wash dishes by hand?

The efficiency of modern dishwashers

According to a study at the University of Bonn, dishwashers use one sixth of the water washing by hand uses, half the energy, and less detergent. So it would seem that in the comparison of dishwashers vs hand washing, dishwashers win hands down. Of course, any environmental question is more nuanced.

For example, if you have an older dishwasher, it can use more than three times as much water as a newer model. Most dishwashers have features you can use or not use. And some people hand wash dishes more efficiently than most people. These factors and more affect the greenest choice.

The average modern dishwasher uses about six gallons of water per cycle, compared with older ones that used from nine to fourteen gallons. If you’re in the market for a dishwasher, though, get an Energy Star dishwasher. It will cost more than comparable other models, but it uses only four gallons of water per cycle and less electricity. So you’ll quickly earn back the extra cost in energy savings. 

Energy usage depends not only on your dishwasher, but also how you heat your water. Gas water heaters, electric water heaters, and tankless water heaters all operate at different levels of efficiency and generate different amounts of carbon dioxide. 

Also, your electric company charges different rates at different times of the day. Try to use the dishwasher when demand is the lowest, at times when the utility doesn’t have to operate expensive peaking plants to meet it. 

Comparing a dishwasher and hand washing

You may have a large built-in dishwasher, a smaller built-in dishwasher, or a still smaller one that attaches to the faucet in the kitchen sink. So let’s consider only a standard 24-inch dishwasher. 

Energy Star assumes such a dishwasher has “a capacity greater than or equal to eight place settings and six serving pieces.” The average faucet uses about two gallons per minute. 

Assuming six pieces per setting plus six serving dishes (54 pieces in all), that gives you about nine and a half ounces of water to wash and rinse each one. In total, it’s about as much water as you’d use for a 90-second shower. If you run two gallons of water into one tub for washing and another two gallons into a tub for rinsing, you might be able to beat the dishwasher. 

Is it possible to handwash dishes and use less water than the dishwasher? Maybe. Is it possible for handwashing to beat an old water hog? The odds are better, but you have to be very efficient in any case. 

How to get the greatest advantage from your dishwasher

The idea of using a dishwasher, environmentally speaking, is to conserve water. Rinsing dishes till they look almost clean defeats the purpose. (So does the garbage disposal.) Let the dishwasher do its job.

But don’t leave big pieces of food on your dishes, either. Scrape food scraps into the garbage. Or better still, scrape whatever is compostable into your compost pail. Make sure all fats, oils, and grease (including excess salad dressing) go into the garbage and not into the sewer.

Space the dishes out properly. If they’re too close together, they won’t get washed properly. Glassware and other fragile items can break by banging together. Pay careful attention to spoons and forks. Don’t let them nest together. They won’t get clean.

On the other hand, run the dishwasher only when it’s full. It takes just as much water and energy to run a half-full load as a full load. 

Cups, glasses, and bowls belong on the top rack. If the manufacturer of anything else says that it’s dishwasher safe on the top rack, then don’t put it on the bottom rack. 

If you have large, bulky items on the bottom rack, such as large serving bowls, make sure they don’t block the sprayer. The sprayer needs to get water to every corner of the dishwasher to get everything clean. In particular, it has to be able to get to every part of the upper rack. 

What you shouldn’t put in the dishwasher

Some things don’t belong in the dishwasher under any circumstances:

• Non-stick pots and pans if you still have any. And that includes the more eco-friendly ceramic cookware
• Cast iron cookware
• China with metallic decoration. [Most porcelain and china dishware is actually dishwasher safe. Just make sure it won’t knock against anything else.]
• Hand-blown glass, fine figurines, crystal, and other delicate items
• Hand-painted ceramics and stoneware
• Milk glass (semi-opaque white dishware, which will turn yellow after too many times in the dishwasher)
• Acrylic dishware
• Brass, bronze, pewter, or aluminum cookware
• Wood
• Many plastics
• Dishware you have repaired with glue or other adhesives
• Anything with paper labels. It’s good to wash jars before you put them out for recycling, but if you can easily remove the paper labels before putting them in the dishwasher, do. Otherwise, they can lodge in the dishwasher drain or stick to other dishes.
• Gold colored flatware 

Surprisingly, modern dishwashers are safe for sterling silver and silver-plated flatware, with some warnings. Make sure that your detergent does not contain lemon or other citric acid, which can harm silver. Don’t wash silver along with stainless steel. Electrolytic action when the two metals touch can discolor and pit the silver. 

You will also have to rinse the silver more carefully than other things in the load if you don’t plan on running the dishwasher immediately. Prolonged contact with salt, acidic foods, or sulfides (eggs, mayonnaise, or seafood) can damage silver. 

Eventually the dishwasher detergent will wear away anything printed on glass. That includes the measurements on glass measuring cups and decorations on drinking glasses You won’t be able to use the measuring cups or enjoy the decorations once that happens. Keep an eye on them. Use the dishwasher until you first notice some damage. Then handwash those pieces. 

Can you put pots and pans in the dishwasher?

If you’re cleaning up after a family or other large gathering, you may not have room for cookware. If you live alone, you may need to put it in the dishwasher just to fill it up before you run out of some kinds of dishes. 

You can put pots and pans in the dishwasher, but only if they’re stainless steel. Note that other kinds of pots and pans are on the list of material that should never go in the dishwasher. The best stainless steel cookware has a copper or aluminum bottom, but it’s not the cooking surface.

On the other hand, you can put most ovenware in the dishwasher. You’ll have to hand wash that aluminum cake or pie pan. Glass or ceramic ovenware is dishwasher safe. 

Whether you cooked something in the oven or on the stove, you may have to let the utensil soak for a while, and maybe even scrub it before putting it in the dishwasher. The dishwasher won’t clean residues from baking, sauteing, or frying, for example.  

How to hand wash dishes

Use the dishwasher. Period. But you’ll have to wash some things by hand. That includes either what won’t fit in the dishwasher when you clean up after a large gathering or what can’t go in the dishwasher in the first place.

To avoid wasting excess running water, wash the dishes in one sink and rinse them in the other. Better still, use two large bowls or wash tubs instead of the sink. After all, they hold plenty of water for dishwashing, but much less than it takes to fill the sink. 

Use one of them, plus a brush and spatula, to rinse dishes before putting them in the dishwasher. 

Instead of letting that water go down the drain, you can use it to water your garden or houseplants. Or you can use it to flush the toilet.

But you’ll probably just pour it down the drain. You can use the same tub to wash the dishes. Use the other one for the rinse water. If you have two different colors—and a good memory—you can reserve one especially for rinsing.

If you have any cups, glasses, or flatware to hand wash, wash that first. Put each piece in the tub of rinse water, then in the dish strainer. If you have a large gathering, someone else can dry the dishes. Otherwise, just let them air dry.

Wash cookware and anything greasy only after you have washed whatever will touch someone’s mouth. 

Some final thoughts on sanitation

How many articles have you seen with titles like “26 things in your home less sanitary than your toilet”? 

Even if you don’t read them, it should be obvious that the toilet isn’t the germiest part of your house. In fact, your kitchen probably has more germs than any other room in your home. And one single-cell germ can become more than 8 million germs before the hour hand on your clock makes two revolutions. 

If you use a sponge in your kitchen, it is the germiest object in your house. 

All those little holes and crevices make ideal germ habitats. As long as they’re warm and moist, germs will joyfully multiply. If you wash your dishes and then use the same sponge on the counter and table, you’re spreading germs from one place to another.

You can moisten a sponge and pop it in the microwave for two minutes. That will get most of them, but not necessarily the ones that have worked their way deepest into the sponge. 

Get a supply of dish cloths. They dry out faster, and germs can only survive a few hours after they do. Toss each one in the laundry after no more than a day or two of use and dry at high heat. 

If you like the idea of a sponge that’s always handy, a silicone sponge is more sanitary. At worst, it doesn’t have deep inner surfaces for germs to hide from microwaves. And it dries faster.

Sources:

21 things you should never put in the dishwasher / Karen B. Gibbs. Today. October 19, 2020 
Avoid these 8 common dishwasher mistakes / Taryn Williford, Apartment Therapy. September 8, 2010
Built-in dishwashers vs hand washing: which is greener? / Collin Dunn, Treehugger. October 22, 2020
Can you put pots and pans in the dishwasher? / Cleanipedia. April 8, 2020
Germs in the kitchen / Denise Mann. WebMD. October 18, 2007