Now this is something that has bothered me for DECADES! Anyone who has ever owned a dishwasher knows that they either baby the thing by pre-rinsing their dishes or their dishes will come out with hard gross all stuck to their silverware and inside their glasses/cups/mugs. Worst of all, this post-cleaning yuck often occurs even when one is careful to clean their dishes before putting them into… the dishwasher!
Well, it’s because dishwashers are built to circulate a pool of water over the food and then evacuate that pool several times through a filter and a small hose. While this approach may appear on the surface to be energy and water efficient, this conclusion was apparently not based on rigorous testing of alternative methods.
Basically, a large volume of water is put into the bowl which causes the existing volume of water to be pushed over the hump in the pipe and down to the sewer, leaving a clean pool of water in the bowl. Total rocket magic, I know.
Imagine if the first cycle of your dishwasher sprayed the hell out of the dishes with super hot water, filling the bowl below the dishes with whatever crud you happened to leave on the dishes, and then flushing it all away in one giant gulp. After doing this, the dishes would already be so clean that they would likely only need a few minutes of rinsing with a small amount of detergent and some warm water. Add on one more quick rinse with clean water to remove the detergent, and you’re done, in ten minutes or less. That’s a whole hell of a lot less water, time, and energy than our “high efficiency” dishwasher, which takes roughly two hours to complete its (often required) heavy cycle. Not to mention that the filters and tubing of the dishwasher wouldn’t need to be cleaned as frequently (twice a week here!), because the detergent and rinse water would be completely clean, thanks to the “big flush” in the first cycle.
Literally every piece of this plumbing technology already exists, so there’s no reason not to make dishwashers in this way.