Dear Home Ec 101,
I have always followed my Mom’s advice about running hot water in the kitchen sink before (and while) turning my dishwasher on. She also says that if you run the cold water at any point while your dishwasher is running, the water in your dishwasher will be cold. My husband recently replaced our sink and garbage disposal and noticed that our dishwasher is only hooked up to hot water.
So, do I really need to abide by my Mom’s rules?
Wondering About Water Temps
Your mom is partially right. Running the hot water before starting the dishwasher ensures the water that fills the machine is hot instead of lukewarm. You don’t jump in the shower the second you turn on the hot tap, right? It takes a moment for the water that has been cooling in the hot water pipe from the water heater to the tap to be flushed out. Typically your dishwasher is hooked into the hot water line
Remember cleaning is accomplished through several forms of energy:
Thermal – the higher the temperature, the more dirt can go into solution. It should be noted that the heating element / timer combo in your dishwasher was designed to boost hot water near 140°F. If you check your appliance manual or the website of your manufacturer, you’ll see most recommend water at least 120°F but not more than 150°F. (140°F is the recommended setting for most home water heaters.)
Physical – in your dishwasher this is the accomplished with spray
Chemical – this would be your detergent (Oh and as an unasked for aside and plug, I’ve been trying out the Smarty Dish by Method, which was phosphate free before there was the voluntary ban on phosphates and it’s friggin’ awesome. I bought it myself, Method didn’t supply it).
Running the cold water while the machine is running shouldn’t be an issue, but running the hot water before the basin of the dishwasher fills ensures your dishwasher starts with every advantage. Having to rewash dishes is far less efficient than running the hot water before starting your machine. You can always catch the water in a bucket and use it (when cool, naturally) for other tasks like plant watering, if water conservation is a big concern.
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