Comments on: AskPablo: The Dishwasher

By: Anonymous

Anonymous — Fri, 20 Jun 2008 14:25:47 +0000

was your dishwasher energy star rated? you said it was at least 28 years old – i like to think that we have made some drastic energy saving measures since then. also – did you try it with turning off the heated dry cycle in the dishwasher? i use the dishwasher with that turned off – run it in the evening before bed – and the next morning the dishes are dry and clean… without the heated dry. i will – as well – stick to the ’scientific’ research.

By: Buff

Buff — Sun, 18 Mar 2007 18:22:33 +0000

I loved your mini study and how it reflected something more realistic. The comments posted to your study are revealing. What should be clear is that people don’t use dishwashers because they are more efficient, they use them to save time. The study out of the University of Bonn, Germany, is what started the long list of sites claiming dishwashers are more efficient.
The study has many flaws of which the most obvious is using 12 place settings comprising 140 pieces as a test basis. That’s four people have three complete formal meals in one day and not washing those plates until after dinner. Most people don’t have 12 complete place settings and would have to wash dishes just to have clean ones for dinner. But the study was conducted with all the dishes at once so no dried on egg yolk from breakfast and no sticky cheese from lunch. The human testers all seemed to have the worst washing techniques averaging almost 30 gallons of water. That would be like filling and draining my kitchen sink 6 times or using my bathtub to wash those dishes. The study also doesn’t claim which model of dishwasher was used unlike your study. This is important because the Bonn study claims the machine used only 4 gallons of water but I can’t find any such machine in the United States, let alone one for sale.
For more information and links to the German study read my blog at: greenwashed.blogspot.com

By: Cathie Tongue

Cathie Tongue — Mon, 12 Mar 2007 23:12:14 +0000

I would also question how scientific this study is as one not actually filling a sink which most people do. Even if based 10litres per sink then 2 washes a day = 20litres conservatively.
Also most dishwashers today use between 12-20 litres to do the same job so it is quite an easy
solution that dishwashers are in fact more economical.

By: Mark White

Mark White — Mon, 12 Mar 2007 21:37:49 +0000

Your study was not very scientific considering that you at the end ssaid that you were running water and not filling a sink. I think 20 litres is about right tho to fill a sink. Most dishwashers now use under 20 litres so you dont really have to be a rocket scientist

By: Brian

Brian — Thu, 01 Mar 2007 10:03:07 +0000

I’ll stick with the scientific study thanks anyway. http://environment.about.com/od/greenlivingdesign/a/dishwashers.htm

By: fefrie

fefrie — Tue, 20 Feb 2007 04:07:58 +0000

One thing that you forget to factor in is the fact that MOST people aren’t really concerned about using as little water as possible, they just have the taps on full (for the pressure)while they rinse, and rinse, and rinse untill they think their dish is clean.
I’d say that the average hand dish washer uses way too much soap and way too much water. I’ve got roommates, I’ve seen how they wash. And the way that people are living these days in our SUV mentality, I’d rather they use a dishwasher.

By: Sam

Sam — Tue, 30 Jan 2007 22:04:14 +0000

the super interesting thing about this issue is that the dishwasher is allegedly “easier” and hence, it exists.
Never mind energy for a moment:
So all the dishes are piled up next to the sink. I have to use water to rinse essentially all the food off of them so that the outlet will not be clogged. I want to use warm water so that my hands will be comfortable.
Why not just put soap in that water, give the dishes the extra second to scrub them completely, and rinse them.
the alternative is bending over forty times to load them into the dishwaser, and then bending over forty times more the next morning to put them all away.
It seems intuitive to me that if the dishes must be rinsed by hand, they might as well be washed by hand, as 50% of the job is done at that point, and the loading and unloading calories can be burned on a hike or a bike ride.

By: Anonymous

Anonymous — Tue, 30 Jan 2007 17:23:30 +0000

I’ve been wondering about this issue for a long time. As you showed, I assumed that handwashing was more efficient. You don’t use electricity (other than the hot water) handwashing afterall…
Thanks for doing the experiment.

By: ecogal

ecogal — Tue, 23 Jan 2007 00:02:50 +0000

Hi Pablo and Emma! Great topic for discussion and nice research! Interestingly, the study at http://www.mtprog.com/ApprovedBriefingNotes/BriefingNoteTemplate.aspx?intBriefingNoteID=286, released last year, came up with the opposite result. They concluded that water consumption (in typical UK dishwashers) use 3-4x less water than washing by hand. Of course, differences in dishwashers and dishwashing habits can make all the difference. Just though I’d share similar research with an opposing conclusion!

By: Anonymous

Anonymous — Mon, 22 Jan 2007 20:23:31 +0000

Wow I am Emma’s teacher in 3rd grade but it looks like she is teaching me things too!

By: Eve

Eve — Mon, 22 Jan 2007 19:53:02 +0000

Pablo and Emma has proven me wrong. I was so sure that the dishwasher was more efficient. The only concern I have is how sanitized are those hand washed dishes?

By: Janice Neitzel

Janice Neitzel — Mon, 22 Jan 2007 18:49:12 +0000

Interesting research, as I keep reading that using a dishwasher (assumption is 4-8 gallons of water) is more energy efficient. Hmm…our’s is only a few years old – I’ll have to check how much water is used.

By: Pablo

Pablo — Mon, 22 Jan 2007 16:17:36 +0000

Anonymous- I was pretty careful with how much water I used while hand-washing. I did turn the tap off between dishes and didn’t have the water running at 3 gallons per minute. But like I said, I could probably have saved more water by using a soapy tub and a rinsing tub.
Thank you all for your great comments! Emma and I had a lot of fun with this experiment and we’re glad that you appreciate our hard work.

By: Anonymous

Anonymous — Mon, 22 Jan 2007 16:14:34 +0000

Wow! I’ve been hoping you would do this comparison for a long time. I suspected the results would be as you’ve stated, but your research gives me great ammo for convincing others.
Question: Were you excruciatingly careful about how much water you used during hand washing? That is, did you turn off the tap between reaching for new dishes?