From memory yes, it's partially about water usage, but dishwashers are in general just pretty good overall about efficiently using energy to maximize "food grime removed" per unit of resources fed in. Even if you're careful with water usage while hand washing, I think a decent dishwasher will beat you.
Another advantage is the dishwasher heats its own water, whereas with hand washing either you need to use a house-wide water heater or preheat water in a kettle or something, which will have its own energy wastes. This of course depends also on how your house's water is heated.
One page I found googling elaborates on these ideas, concluding that you could potentially be more efficient hand washing, but only with a lot of effort: https://www.treehugger.com/built-in-dishwashers-vs-hand-wash...
I once ran the dishwasher with the outlet hose in a bucket because the drain pump was on its way out. I expected to have to empty it several times, but at the end of the cycle there was less water in it than I would use to fill a washing-up bowl to do the dishes by hand (and the amount of dishes it cleaned might have required more than one bowl).
As for water usage, think first of agriculture, then industry. Only after that do cities come into play. Cities are relatively small water consumers.
>As for water usage, think first of agriculture, then industry. Only after that do cities come into play. Cities are relatively small water consumers.
Where do those agricultural products get sold and eaten?
<insert screeching about "taxing muh negative externalities" here>
There are also some water pumping and treatment costs (more energy), but they can be ignored as insignificant.
Their rational explanation is probably "how you can be so stupid for not knowing that common knowledge".
And well, even though I am indeed a treehugger, I also knew about the efficency of dishwashers before and also assumed it to be common knowledge, but I would never downvote someone because of a genuine question adding to the conversation.
Yes: if your dishwasher has the Energy Star rating then it must use ≤15L of water using the normal cycle per the EPA. This is half the volume of a small sink and a one-third or less of larger ones.
Most people run the water. In the US the average flow rate of a kitchen faucet is 8 L/min (2.2 gpm), so you can quickly use up 15L even just rinsing.
My faucet is very slow, about ~1gpm (I timed it once upon a time because I wanted to be able to put a number to how slow it is). When hand washing I run at maybe 1/4 or less of that. Everyone else in my household runs it at less.
I think part of it can also be (at least for me) upbringing. We always handwashed our dishes, and only used the dishwasher a couple times per year for big events.
Firstly, you can't wash with cold water because soap doesn't activate with cold water, hot water also kills bacteria and helps cut through grease.
Fats themselves are hydrophobic and without activated soap you wont get them off... enjoy your "filmy" dishes.
Second, humans expend a lot more energy than you think. The act of standing and using our arms releases varying amounts depending on physical fitness but averages somewhere in the 1kg/h ballpark. https://www.jstage.jst.go.jp/article/jjphysiol/50/2/50_2_199...
Dishwashers use about 1800 Watts and are commonly run for 30 minutes, the average co2 in the USA is 0.92lbs per kWh.
Meaning it's _basically_ the same.
Then there's the freshwater usage, which is the real kicker, because dishwashers use significantly less freshwater, and freshwater filtering is the largest environmental impact of washing dishes (not the direct co2 output).
Bunch of pseudoscience. I've never noticed any difference between washing with cold or not.
hot water also kills bacteria
Ultimately doesn't matter because they're all being washed away by the soap molecules anyway.
The act of standing and using our arms releases...
Lol, are you seriously trying to reason that what little energy you burn is more than a dishwasher?
Soap not activating when cold is not "pseudoscience", it's just a fact. Like grease doesn't become liquid unless heated. It's a similar principle.
> Ultimately doesn't matter because they're all being washed away by the soap molecules anyway.
If they bind, but, I'll give you this one.
> Lol, are you seriously trying to reason that what little energy you burn is more than a dishwasher?
Humans are pretty shitty at expending energy. This is one of the largest arguments against cycling long distances (though those arguments I don't agree with, but we're talking about total Co2 output here).
That may be true for most laundry detergents, which have to pull grime out of fabrics, but not simple dish soap. Just look at how well Dawn works to take oil off concrete, for example. Nobody's heating that up.
Once you’ve removed the bones and massive solids, the modern dishwasher can do an astounding job on the rest. Put a little detergent in the prewash (or on a Bosch, just in the tub) and let the machine do the work. (I also grew up washing dishes before putting them in the dishwasher. It’s almost never needed now, but old habits die hard.)
(essentially, the instructions are to remove the same things from the dishes you would remove if hand washing them in a sink with no disposal...)
I thought the same, and then it turns out that my garbage disposal was broken and obstructing the speedy removal of waste water from my washing machine. Fixed that and now my dishes come out clean.
