Today, I washed my hands at the kitchen sink while making lunch, and was unexpectedly chastised by my partner because she had just started the dishwasher. Apparently, she has recently come across something that has convinced her that running the hot water in your sink means the water that enters your dishwasher will be hotter (checks out), and thus the dishes will be cleaner. I tried searching startpage to see if this is real, but I couldn’t make it through even one llm-slop-ticle about it before my eyes rolled back into my head, so here I am asking y’all: chat, is this real? Doesn’t my dishwasher have a heating element? Is there any meaningful difference between heating the water with a hot water heater vs a dishwasher, other than I can’t use my sink while the dishwasher is filling and I have to pour a bunch of cool water down the drain?


Yes. Foolishly most of the less expensive dishwashers don’t heat the water themselves, and the first cycle is more effective if it doesn’t have a period of using cool water from the pipes until the hot water arrives.
I was skeptical at first too but it truly works.
But it may be worth clarifying to your partner that once the water is coming out of the tap hot, the water in the hot pipes is already hot, so turning the tap to cool at that point no longer negatively impacts the dishwasher.
The important part is getting the cool water in the hot water pipes that has been sitting there flushed out before starting the dishwasher. If that’s already achieved, then what you do with the tap doesn’t matter anymore