Should I Wash My Dishes Before Putting Them In The Dishwasher?

As an anthropologist, I find the interface between technology and the larger culture in which it is embedded fascinating. You all know the old story of the family cook who habitually cuts the ends off the roast before slipping it in the oven. One day her child, hoping some day to be the family cook, asks why this is done. It turns out that nobody can remember, and the matter is dropped. But the question comes up again, at a later family dinner, this one attended by great grandma, who was the family cook a generation ago, and of course, she knows the answer.

"Back in the day," she says, "It was the depression. We weren't able to just go to the store and buy whatever we wanted, like people these days."

Grandma always managed to work in a mention of how poor they were back in the depression. But this time it was relevant. "We had only one roasting pan," she continued. "It was only 14 inches long and the roast was always a few inches longer. So I'd cut the ends off."

And of course, ever since then, subsequent generations had learned to cut off the ends of the roast because that is how grandma did it, and there must have been some reason, though nobody knew what it was. And now, the roast, be-ended, sits small in the large stainless steel double handed Williams Sonoma roasting pan.

I think that is how some people load their dishwashers. Back in the day, dishwashers weren't very good at washing dishes. They were really status symbols that did little more than rinse off the dishes that you'd already scraped and run under the faucet. You put dishes in the dishwasher that already looked pretty clean. The role of the dishwasher was to remove the few remaining cooties (or dog saliva for some households) and, if you kept up the supply of anti-spotting juice, to make sure that the glassware was shiny-clean.

Dishwashers have changed. A reasonably good dishwasher, not even the most expensive or fancy, does a much better job at washing dishes. Even cheap ones, probably. The difference in price between dishwashers is mostly a matter of bells and whistles and whether or not it has a stainless steel front, that sort of thing. Inside, the engineering of how to spray water on dishes from various angles for a very long period of time has been worked out. These days, you only need to remove the large parts, the parts that remain because people these days, unlike back in the depression when there was not enough food, have forgotten that they should finish the food on their plate. Even the chicken bones. Back in the depression, people ate the chicken bones.

When you wash dishes in the sink, you use water and energy. The energy is to heat the water, but also, the water itself requires energy to process and pump. When you wash dishes in the dishwasher, you use energy. Again, heating and getting water are factors, but also, the dishwasher has a pump and may have a water heating element, and of course, a drying element. More on the drying element later.

If you did a complete hand washing job on your dishes, then ran your dishes on a full cycle in the dishwasher, you would be using way more energy and water than required to actually get the dishes clean. But if you only hand wash the dishes a little -- scrape the plates than run them under the water -- maybe you are using less energy and water. But the fact remains, if you just scraped the dishes minimally and the put them in the dishwasher straight away, with absolutely no rinsing, you will use a minimal amount of energy.

Some people claim that they do hand washing so efficiently that they are using less energy than a dishwasher would ever use. Such folk eschew the dishwashing machine entirely. However, dishwasher experts claim that this is only rarely the case. The dishwasher uses a small percentage of the water and energy you use in hand washing.

Chis Mooney has written up the current research on dishwashing efficiency. His Washington Post article cites research from the EPA, the Natural Resources Defense Council, and the American Council for an Energy Efficient Economy. The bottom line: Don't pre-rinse the dishes. Just put the damn dishes in the dishwasher. Oh, and you think your hand washing is efficient, do consider the possibility that you don't really know that. You just think that because you want to. It is almost certainly the case that you can't really prove that and it is likely (but not impossible) that it simply isn't true. From Moony's Washington Post article:

... dishwashers just keep needing less and less water (and energy) because of improving appliance standards, even as they get better and better at using it.

“While it may be possible to use less water/energy by washing dishes by hand, it is extremely unlikely,” Jonah Schein, technical coordinator for homes and buildings in the EPA’s WaterSense program, said...

“In order to wash the same amount of dishes that can fit in a single load of a full size dishwasher and use less water, you would need to be able to wash eight full place settings and still limit the total amount of time that the faucet was running to less than two minutes,” he said.

“...modern dishwashers can outperform all but the most frugal hand washers,” adds the American Council for an Energy-Efficient Economy.

This applies to modern Energy-Star rated dishwashers. Which, if your dishwasher is reasonably new, is probably your dishwasher. And by new, we mean up to several years old because this has been true for a long time. Moony's story has further details on exactly what makes dishwashers more efficient.

So, this is like cutting the ends off the roast. In the old days, you needed to wash your dishes before you washed your dishes. Now, you can just wash your dishes. But do you? Or are you still cutting the ends off the roast?

(It is unfortunate for the dogs that they lose in both cases.)

Moony also talks about the drying element in dishwashers, and I have a word or two to say about that as well.

Consider the term "dishwasher safe." In my household, everything is "dishwasher safe." This is because I put everything in the dishwasher. If something is not dishwasher safe, it gets weeded out. Most things that are not dishwasher safe are subject to heat damage when the drying element comes on. I installed our present dishwasher about five years ago. The heating element has yet to come on. Well, it did by accident once and boy, did that smell bad. (If you don't use the heating element, it tends to accumulate a layer of stuff that smells bad once you do turn it on). This is not to say that the only unsafe thing in a dishwasher, if you are a plate or a bowl or something, is the heating element. The water in a dishwasher is hot, and the chemicals are caustic. We have a number of coffee mugs that no longer say what they formerly said because the cheap printing process used to make them did not stand up to the slings and arrows of outrageous technology. Those coffee mugs that change on the outside when you put hot coffee in them? That works because of a layer of cheap plastic on the outside of the cup. My Doctor Who mug (where the Tardis disappears and reappears) lasted one day. I still have it but it is a simple black mug with no evidence that the Doctor ever existed. And, when I pop in "clean recyclables" like a peanut butter jar made of plastic, that stuff comes out distorted and half melted, but not really melted and it isn't a problem; It was on the way to the recycling bin anyway.

If you never turn on your heating element you will use a lot less electricity and many non-dishwasher safe items survive the dishwasher. I'm not making any promises, I'm just telling you what I do. Don't worry, the dishes get dry. Modern dishwashers run some air through after the washing is finished on a full cycle, and if you open the door, physics, in the form of evaporation, will work very well.

This, of course, is a metaphor for many other things. Consider the culture of your use of technology. Do you let your car warm up for a long time on a cold winter morning? To you leave it running when not actually driving because you heard it takes more energy to start it than to run it for a while? Do you leave florescent lights on in the office all day even when the rooms are empty because you heard that was more efficient? As usual, you are probably doing it all wrong. Not your fault, it is just how our brains, and our cultures, work. But you can change and help make a difference.

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I just Googled "dish washer." They appear to be popular, since there seems to be billions and billions of different ones available for sale, though I don't recall ever seeing one. Where I was born and raised (near Black Mesa, Arizona) there was (and is) little water, and there was (and mostly is) no electricity, but even down the mesas where the "rich Navajoes" lived no one had machines that washed dishes. The whole idea of using a machine to wash dishes just freaks me out.

My grandparents, and my parents, and my siblings used a wet cloth to wipe dishes, and the cloth was rinsed in a bucket of water. Water came from a government-drilled well, pumped by a AEROSTAR wind turbine, where dozens of households would go with containers to get water. If the wind didn't blow for a few days, no one had water.

I can imagine standing around the well, waiting to fill my two-gallon jugs, and asking people how well their dish washing machines wash their dishes. "Does the heating element dry them fast enough?" Heee!

When I was about 9 years old the government came in with a generator and an electric pump to replace the wind-powered pump. This meant that when there was no fuel for the generator, we didn't get water. It also meant that everyone had to avoid standing on the concrete casement when holding down the power switch, otherwise we would get a terrible shock. Complaints flooded into the chapter house, and those complaints were sent to the BIA, and the BIA sent the complaints to Richard Nixon, who at that time had his own problems, and there it sat.

Then one day a Hopi came along looking for water, and since no one cared if a Hopi got electrocuted, no one bothered to tell him about the faulty wiring. After he stopped jerking and shaking from the shock, he went away and later that night "someone" ripped out the wiring, hauled up and destroyed the pump, and vandalized the generator. All of us non-Hopis thought "why didn't we think of that?"

A few weeks later we got our wind-powered system back.

The moral of the homily is, if it ain't broken, don't fix it.

By Desertphile (not verified) on 13 May 2015 #permalink

Regarding regulations for washing machines, I found a hilarious web site that says, in part:

As of May 2013, dishwasher manufacturers are not going to be allowed to make or sell a machine that works.

It is from a "free market" fundamentalism web site:

By Desertphile (not verified) on 13 May 2015 #permalink

I tend to rinse the dishes, especially if the dishwasher won't be full by the end of day. Otherwise it starts to smell, and the food sticks to the plates.
Your results may vary.

By MobiusKlein (not verified) on 13 May 2015 #permalink

I hand wash because the number of dishes in a 2 person house is very small and not worth the effort and I don't even use a sink of water.
Also there is no such thing as drying in a dish washer. The dishes are always wet no matter when they are taken out.
I dry my dishes with a small economy fan just moving the air over them, when I do use the dishwasher (large gatherings) I also dry by opening the dishwasher and using the small works way better and uses little electricity.
When using the dishwasher I never pre-wash (the idea defeats the entire purpose of the dishwasher) and have never had a problem with dishes not coming clean.

I'm sure it would be difficult to beat a modern dishwasher when full, yet how many people turn the dishwasher on when only partly full? As L.Long pointed out, with only one or two people in a household, it may be more efficient to hand-wash. Leaving in dirty (and increasing smelly, over time) dishes until a full load is reached doesn't sound appealing. I sure wouldn't want to be the one to have to load in the last of them after a day or two of marinating.

There are only two people in my household, and we don't go through a lot of dishes anyway. I can often wash the dishes on a single cycle of my pressure tank, and it doesn't take the well pump very long to re-pressurize. I always air dry on a rack. I'd really need to see some more numbers to be convinced I should buy a dishwasher (which would require energy to manufacture) to save energy in the long run.

We don't have room in our kitchen for a dishwasher. We had a portable for awhile but it took up too much room. As L. Long says the amount of dirty dishes two people create in a day is minimal. I just give them a quick rinse, wipe them clean with a soapy washcloth (water not running), then a quick rinse and into the drying rack it goes

By Doug Alder (not verified) on 13 May 2015 #permalink

We can accept the claim about hand "wash[ing] the same amount of dishes that can fit in a single load of a full-size dishwasher"...

But it should be obvious that if one has a single place setting to wash, the dishwasher will be more wasteful (as it is programmed to wash what it expects to be a full-size load, using that amount of water & power).

The important question is: What's the break-even point where it's better to hand-wash than to use the machine?

(Yes, the pre-supposition is that, as with #3, you are not in a position to leave crusty, slimy dishes to rot in your dishwasher for several days to accumulate that full load.)

By Brainstorms (not verified) on 13 May 2015 #permalink

P.S. The greywater from hand-washing OUR dishes lives on to water our garden & house plants... That requires rather unusual (though not unheard of) plumbing arrangements to accomplish with a machine washer. Local laws may have a say in that, too...

By Brainstorms (not verified) on 13 May 2015 #permalink

Kengi, yes, the diswasher should be full! I think people usually do that.

I have a household with three people including a five year old, and occasionally one more. We have no problem filling the dishwasher. I think people worry necessarily about that dried on food. Dishwasher engineers know about that. Dried on food gets undried on during the process.

There certainly are a few items that no amount of mechanical washing will wash off, but for the most part you can leave your dishes in there for quite a while. If you don't think so, just try it and you may be surprised!

If two/three people cook their own food, prepare lunch to bring to work/school, etc. they will use a lot more dishes. If they eat out a lot (i.e. a few dinners a week, lunch at work, etc.) they may not. I work at home so there are usually lunch dishes. I cook the vast majority of our evening meals, so there's pots/pans/dishes/ etc. I can see where some will hardly ever fill a dishwasher.

A while back I lived (in a 2.5 person household) with a very small kitchen. We made room for a half size dishwasher. That worked OK. Hard to get them, but you can. We ordered it at Home Depot. It was not half the cost of a regular dishwasher, by the way!

Yeah, portables are a pain in the ass. I've had those too.

Again, on the encrusted dishes. There is no real difference between a ceramic, glass, or stainless steal surface with one day dried on food gunk and three day dried on food gunk, when it comes to what a dishwasher does.

That is a valid hypothesis...I love the story about the chicken recipe that was passed down through the generations, I refer to it when I ask someone why they do something or why they have a certain opinion and they have no reason.

By Roxanne Porozinski (not verified) on 13 May 2015 #permalink

Wasn't there a study recently with results to the effect that bacteria count on dishes post-dishwasher was dramatically lower if you'd pre-rinsed them?

By Ketil Tveiten (not verified) on 13 May 2015 #permalink

Ketil, I'd love to see a link for that. Doubtful, but if so, don't forget that we need those bacteria for our endoflora!


By Max Millhiser (not verified) on 13 May 2015 #permalink

Hmm, my google-fu is failing me. It came up in the (Swedish) news about a month ago, as I recall.

By Ketil Tveiten (not verified) on 13 May 2015 #permalink

Greg Laden #9

I don't doubt the ability of a modern dishwasher to clean encrusted dishes. I doubt the willingness of people to deal with smelly dishwashers after a couple of days of food going bad inside of them. I suspect they would rather run the dishwasher partly empty rather than have to deal with the smell of rotting food when they open the dishwasher.

I'd be interested in seeing studies on consumer habits of dishwasher use as well as try to get a better feel for how much energy I use manually washing dishes. Not sure how to approach the latter, but I'll give it some thought. As for the former, I saw this article:…

but it's behind a paywall...

I've been reading several studies on water/energy use and most seem to show similar results. This one is fairly typical:

It looks clear that many people washing dishes manually "over-clean" and waste a great deal of water and energy. Given that, if everyone were to get and properly use a dishwasher (no pre-washing and only washing full loads), there would be a significant energy and water savings.

Of course, most studies show that even people with dishwashers often manually clean dishes, and I still haven't seen numbers on how full they load dishwashers before washing, but given the frequency of dishwasher use, and that manual washing is used as well, I'd guess most people are running the dishwashers on partial loads.

So, it looks like the average dishwasher user as well as the average manual dishwasher are both energy and water wasters, as your original article pointed out.

Personally, I've long been concerned over energy and water usage, so I'm careful when washing dishes, and would be one of the outliers in usage anyway.

This discussion has made me think about how I could improve my efficiency even more. I use very little hot water, so most of my energy use is probably from the well pump. Rather than a dishwasher, I would probably put that money towards solar panels and batteries to remove the pump from the grid, which would make most of my washing-up energy renewable, as well as give me the advantage of having unlimited water during a power outage.

I think I'd prefer that to a smelly dishwasher...

In the version I heard, the grandmother cut the *ham* because her old *stove* was too narrow.

We have a beagle pre-wash. Everyone.should. It's so efficient that sometimes I mistakenly put dog washed dishes back in the cupboard thinking they're clean.

Call me a dreamer, but I look forward to a day when it won't matter if I squander energy in my kitchen, or my car. I'll be able to heat my home as toasty warm as I want in the winter, and keep it as frosty cool as I want in the summer.

Because all my energy use will be from carbon-free electricity, and it will be cheaper than hell compared to fossil fuels.

Would that that day comes sooner rather than later.

By Gingerbaker (not verified) on 14 May 2015 #permalink

Some years ago I did a bunch of testing & experimentation with water & energy conservation in household laundry, refrigeration, and dishwashing, to develop my current practices.

The most-efficient practices are highly dependent on the number of people in a household and their various relevant habits.

Firstly, size the appliances to the size of the household. NOT based on "when we entertain," but based on the modal average: the normal day's usage. (This is a particular peeve of mine: much inefficiency occurs when homes and their infrastructure are sized for "entertaining large groups." Oversized living rooms, oversized kitchens, oversized TV screens, oversized appliances, etc. are the result, with enormous waste. This is like buying an SUV "for hauling the kid's baseball team around," when in fact it's used for single-person commuting most days of the year.)

The correct size of dishwasher is that for which one day's dishes etc. make up a full load. That prevents the "stinky dishwasher syndrome" and makes the task easy and routine: after dinner, run the dishwasher. (When you have 20 people over for Thanksgiving, do multiple loads that night and don't complain: the total amount of loading & unloading is the same, the only difference is the number of times you add detergent and press the Start button.)

The wastewater output of any dishwasher is through a hose that's connected to a drain pipe. That hose can easily be replaced with one that's long enough to be brought out to the front of the kitchen cabinets, where it can fill a 5-gallon or larger bucket. (NOTE: Be careful to set this up so the hose will not be expelled from the bucket under force of the water discharge: you want the water in the bucket, not all over the floor.) The water in that bucket can be used for toilet flushes or watering non-food plants (unless you know that the detergent won't have some unforeseen nasty effect on food crops in a garden).

For smaller households, arguably up to 4 people depending on cooking/eating habits, a countertop sized dishwasher is sufficient. I'm using a unit made by Danby that cost less than $300 and does an excellent job. The final rinse is a sanitize cycle that uses the heating element to get the water up to 180 degrees. After that, I leave the door ajar, and the retained heat in the dishes and cabinet is more than sufficient to get them bone dry in less than an hour.

For dishes and for laundry, the rinse cycles are the issue for water usage.

Rinse is basically active dissipation, to dilute the level of detergent that remains on/in an article, to a level that is acceptable. It usually takes two rinses to get an acceptable result, but with care you can get it down to one rinse. Most people use far too much detergent on both dishes and laundry, as evidenced by the suds in the second rinse cycle. (Try washing your clothes with no added detergent: you'll still see suds from the detergent residue that's already in the fabric from overdosing on detergent most of the time.)

Detergent manufacturers recommend higher amounts than needed, to ensure that the product does a complete job of cleaning. Yes they sell more detergent this way, but the primary motivation is to ensure that the product works completely, thereby keeping loyal customers.

You can and should experiment with reducing the dosage of detergent in laundry and dishwasher, to a level that will do the job correctly and not require multiple rinses. For dishes this will involve pausing the cycle after the wash cycle, to check that all food residue is removed, and then pausing it again after the first rinse to check for detergent residue on dishes. (However if you recycle the graywater to toilet flushes, rinses aren't a big deal as long as they don't exceed the demand for toilet flushes between loads).

Detergent dosage will also vary as a factor of the quantity of oil- or fat-based material to be removed from dishes (or clothes). This is the reason for using a manual dish brush or sponge to remove visible food particles before putting dishes in the dishwasher. The brush or sponge only needs to be damp to do its job, so there's no need to run the water in the sink for this.

For washing dishes in the sink, use any appropriate size of container to catch the used water, and then dump it into a bucket to be used for toilet flushes. As with graywater from the dishwasher or laundry, use this water as a priority so it will not have time to stagnate (or add a few drops of bleach).


OK, so now I'm off to do laundry tonight. For this purpose, the clean water input comes from a tank that was filled with the purge water from the shower (the cold water that comes through before the hot water), and the graywater output will also be used to flush the toilet.

All of this stuff is easy if one just gives it some thought and the willingness to experiment.

About showers:

Adjust the thermostat on your hot water heater to the temperature that is comfortable in the shower (trial & error: empirical method). Thus you will only need to use the hot water faucet in the shower, and you can turn it down to a bare trickle while soaping up. This is better than having to rush through a shower at full-blast, and much better than having to fiddle with both hot and cold controls to adjust temperature. For applications that require hotter water, heat what you need, e.g. in a coffee pot or tea pot, or let the clothes washer or dishwasher heat it up for the cycle.

Another peeve of mine are those obnoxious "single control" faucets in showers, that only turn on full-force and only allow adjustment of the hot/cold balance: another piece of incredible waste for no good purpose. To deal with that, get a shower nozzle with an "off" button and learn to adjust that button to the comfortable trickle while soaping up.

Lastly, with a few simple bits from the hardware store, you can build an attachment for the shower that connects via hose to a garden spray nozzle. Using that nozzle to wash yourself in the areas that the flow from the overhead nozzle can't reach effectively, is more efficient than turning up the flow to the overhead nozzle.

Really: all of this is easy if you're willing to experiment.

Remind me to give Gregg a large roll of heavy duty aluminum foil for Christmas, to transform his quality of kitchen life.

By Russell Seitz (not verified) on 16 May 2015 #permalink


"Firstly, size the appliances to the size of the household. NOT based on “when we entertain,” but based on the modal average: the normal day’s usage. "

I would even broaden that principle. People may, for example, buy a car with a v8 engine, a hitch, a lot of power, and a high form factor (a big SUV essentially) because of that two or three times a year they have to tow a boat and the four or five times a year they have a big purchase at home depos. But if they got a small super efficient car that served their needs every other day of the year, and rented a truck (and home depot will do that for you for those trips) when needed, or hired someone to do the towing, there would be huge savings in their money and their Carbon use. I know someone who had the need to tow two boats a year, about a mile one way, twice a year, and always bought such a vehicle. When they upgraded one of the boats to be too big to tow, they started having the marina tow it for them. Adding the marina towing both boats would cost a total of about one gas fill up, once a year. Switching that vehicle for a good hybrid (for the range) would reduce annual gas consumption to about 20-25%.

I never pre-wash any of my dishes, it defeats the whole point for me! It's only worth cleaning them if they're still dirty when they actually come out really.

By Ian Jeffrys (not verified) on 31 Oct 2015 #permalink

Thanks for this post. I was also having such a doubt :D

By teresia davis (not verified) on 01 Mar 2016 #permalink

Actually it depends on the dishwasher model type. But anyways, It'l be good to scrape off larger food wastes. But most dishwasher manufacturers say there is no need to do a complete rinse as it's an additional wastage of water. We have bought an AEG dishwasher from 'Best Brand Appliances', Canada before 2 years. We don't rinse dishes before placing in dishwasher? :)

By Sherry Milone (not verified) on 01 Mar 2016 #permalink

My name is Roby, belong to Gold Coast, Australia but right now, I am in NYC. I got your blog post from FB timeline which is shared with my friend Nat. I review this information based post and like it. I bought new dishwasher recently by using the an outstanding price comparison website …PayLessDeal, they provide huge collection of latest models/brands, which made easy to choose according to your budget. I bought Fisher Paykel DishDrawer integrated Dishwasher and its working well. Before putting dishes/plates in dishwasher they should be rinse normally.

By Robyn Mac (not verified) on 12 May 2016 #permalink