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Claim: 8 dishes in washed in dishwasher every night uses less water and energy than 2min tap run in sink.
Raised first by Proctor and Gamble, Malcolm Gladwell, revisionist history podcast
9L water used for hand washing (on average), handwashers more likely to wash more regularly so could use up to 20-30L/day versus 13L for average dishwasher run.
1.1kwh per wash, sink washing varies massively, they're assuming natural gas heated water
9L in sink to wash meal for two - 8 things, 13L for dishwasher, hence the break even point of 8 items.
They didn't look at energy to make and ship the dishwasher (nor upgrades given they were just talking averages) though reckon it will be paid off over its life (assuming their higher figures)
Plus, dishwasher owners still have to use sinks for non-dishwasher stuff like wooden bowls and chopping boards and posh glassware.
So, given our water is either cold or heated with electric (depending on the items) and normally we use half a sink to wash a day's dishes (more like 6 items per meal, not 8 items only) I'm still confident -our- washing up habits are more efficient than any of your dishwasher shenanigans.
Yeah nah
Also, does it factor in the manufacturing of the dishwasher? Because by not owning a dishwasher I'm already well ahead of anyone with one.