Tip of the day: pre-rinse in cold water


In this day and age, most of us have dishwashers, and yet there’s still quite a bit of controversy over how to wash dishes. Some wash every dish by hand. Some just throw them in the washer. Others wash the dishes by hand then put them in the dishwasher to make sure they get really clean?

This is an energy efficiency blog, so I’m going to look at this from an energy standpoint. If you live in New Mexico or elsewhere where water is in extremely short supply, you’ll probably have methods that are more water efficient.

You might have noticed that things just aren’t washing as well as they used to. You’re not imagining things! In fact, new soaps are “phosphate free” and people all over are complaining that dishes no longer come out clean. I certainly have. Here’s one article about the topic.

Because of this, more people than ever are hand-washing dishes. Either as a pre-rinse or giving up on dishwashers. So energy efficient rinsing is becoming even more relevant.

No matter how you eventually wash your dishes, I recommend using cold water to pre-rinse your dishes. The purpose of the pre-rinse is to get rid of the large chunks of food and stuck on residue – things that don’t wash well in the dishwasher. Some things, like pancake syrup and other non-greasy residues are best soaked for a little while. That dissolves the material and makes it almost clean with a quick rinse.

You might recall way back in my articles on water heaters, I talked about the waste of hot water due to all the water left in the pipes. When you rinse with hot water, you are first wasting all the water in the pipes while you wait for hot water, then wasting all the heat in the water after you stop using the hot water! That can easily waste a few gallons of hot water every time you rinse a dish.

When you rinse in cold water, you’re saving these several gallons, plus whatever water you actually use for the rinse. There’s little reason to use hot water for pre-rinsing dishes unless you’ve got something really baked on or greasy. In that case, you might have to result to hot water and soaking.

Some people might question “why rinse at all?” Usually, there’s a time delay between when you load the dishwasher and when you run it. During this time, any residue will harden onto the dishes, making it much harder to rinse off. You’ve seen it – you end up with a crust, like concrete on your utensils and dishes! Many dishwashers really struggle with trying to get these clean. So after you wash the dishes, you have to wash them again. That’s doubly wasteful!

In addition, most modern washers have  a “smart wash” setting that looks at how clean the water is that’s rinsing the dishes. It will continue to clean the dishes until it thinks they’re clean. If you pre-rinse with cold water, you save considerable dishwashing time in the machine, further reducing your energy usage.

In energy efficiency, the little things add up. Eliminating the “hot rinse” from your pre-dishwasher routine will save you hundreds of gallons of hot water every year.

So what’s your favorite dishwashing method for saving energy?

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