Timeline for Does a dishwasher consume less water than manual dish washing
Current License: CC BY-SA 3.0
21 events
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| Aug 22, 2022 at 20:15 | comment | added | PJTraill | Another often overlooked consideration: we often have some items that seem unsuitable for the dishwasher, so do a manual wash anyway. In this case the lower marginal resource costs of washing more items become relevant. | |
| Aug 22, 2022 at 11:00 | comment | added | PJTraill | Here is a fairly neutral life cycle analysis of various methods in the US including observed behaviours and best practices. The emphasis is on greenhouse gases but also looks at water, energy and finance. Conclusions: running tap just terrible; manual best practices yield lowest emissions; machines use less water than even best manual methods; manual cheaper unless time monetised. | |
| Aug 22, 2022 at 10:03 | comment | added | PJTraill | That themselves give away that it is not a fair comparison: “comparing the average behaviour in manual washing with a fully loaded average dishwasher”. | |
| Jun 6, 2014 at 20:24 | comment | added | drat | @MartinSchröder the 121l is for 6*2 place settings, so it's just about 20 litres per washing-up which is not so much. | |
| Jun 6, 2014 at 18:39 | comment | added | Martin Schröder | 121l is nearly a bathtub. If you use that much water to wash your dishes, you have a problem. | |
| Jun 4, 2014 at 3:34 | comment | added | John Lyon | Dishwashers have also improved recently in terms of water consumption - some of them even store the final rinse water from the previous wash to use as the wash water in the next. My dishwasher uses 13.9L for a full standard wash (14 place settings). | |
| Jun 4, 2014 at 0:39 | comment | added | Izkata | @DavidRicherby Our family of 5 filled the dishwasher every 0.8 days pretty regularly (that is, every couple of days we had to run it twice in a day) ;) | |
| Jun 3, 2014 at 19:30 | comment | added | Bob Jarvis - Слава Україні | @Michael: depends on the brand of dishwasher. Our Braun insists on having the incoming water hot or it won't run the cycle - which is a royal pain in the drain! (But this way the manufacturer can claim lower energy usage). :-( | |
| Jun 3, 2014 at 19:15 | comment | added | Braiam | @BobJarvis the Dish Washer Makers Association ;) | |
| Jun 3, 2014 at 15:35 | comment | added | Michael | @drat i have to flush more than 5L of water through the pipes just to get the water hot! (plus the dishwasher doesn't care, it heats the water up itself) | |
| Jun 3, 2014 at 14:23 | comment | added | Bob Jarvis - Слава Україні | Who funded this study? | |
| Jun 3, 2014 at 8:55 | comment | added | Steve Jessop | @drat: it's a little bit more like you're saying "the fastest runners are unlikely to be faster than a cyclist" when in point of fact the fastest runners in a small sample have been measured to be about the same speed as a typical cyclist. The correct interpretation is that the fastest runners in the population are likely even faster than the fastest in the sample, while cyclists (dishwashers) don't show much variation from their designed speed (water consumption). The overall conclusion about averages is pretty sound, but talking about the "best" based on a small random-ish sample is suspect. | |
| Jun 3, 2014 at 8:53 | comment | added | drat | I think it's a little bit like saying walking is faster than a bike while reasoning that a marathon runner is faster than a 3-year old on a trike. | |
| Jun 3, 2014 at 8:52 | comment | added | Steve Jessop | @David: I think you're on to something here in the interpretation of the evidence. The "best" manual washers in fact can beat the dishwasher (albeit modestly). What's unlikely is that any given person is among the "best" manual washers and knows it with sufficient confidence to eschew the dishwasher. Especially given the Dunning-Kruger effect. | |
| Jun 3, 2014 at 8:45 | history | edited | drat | CC BY-SA 3.0 |
added 75 characters in body
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| Jun 3, 2014 at 8:44 | comment | added | drat | Yes, but by saying this you are comparing the most water-saving hand washers with the most wasteful machine washers. A water-saving convert is unlikely to become totally wasteful and let the machine run empty. Also only 1 person in the study used less than 5 litres, so for most people even a half-empty machine will use less water. If you read the study, you'll also see that they did use different modes for hand washing (fig 7, 3*2 place settings + pots, 6*2 place settings or 1*12 p.s.), this explains the spread from 83 litres (3 p.s. + pands) to 121 litres (6 * 2 plates) mentioned above. | |
| Jun 3, 2014 at 8:19 | comment | added | David Richerby | For reference, I just measured my kitchen sink and it's about 40x40x15cm, which is 24L filled to the brim and, say, 12-15L filled to a more sensible amount. Washing 12 place settings in a single sink-full would be pushing it but 6 goes just fine. Also, note that the comparison relies on the dishwasher being fully loaded, which is fine if just run it every few days when it's full (or have a family of 12!) but not if you wash more often. There seem to be lots of this kind of caveat, which need to be made clearer for the comparison to make sense. | |
| Jun 3, 2014 at 8:12 | comment | added | drat | Yes, I guess that is what makes the difference between the 4 litres and the 90 litres. Unfortunately they don't address this issue in the puplication. Seems however that even a sink full of water (assuming those are the low-end points) is more wasteful than using the dishwasher. | |
| Jun 3, 2014 at 8:10 | comment | added | David Richerby | Presumably, this is heavily dependent on whether you wash under a running tap or in a sink full of water. | |
| Jun 3, 2014 at 6:49 | vote | accept | Gilad Naor | ||
| Jun 3, 2014 at 6:06 | history | answered | drat | CC BY-SA 3.0 |