Dear Home Ec 101,
Lately I’ve been hearing about using cold water when doing laundry, in order to save energy. I have always washed everything in warm water. Can my socks, my toddlers clothes, and my husbands workout clothes really get clean using cold water?
Tepid in Topeka
When I first launched this site, I had no clue how often my chemistry background would be used.
I cannot give you a simple yes or no answer to this question. I know “Can I use cold water to do laundry” sounds like a simple question, but there are many factors at play. How cold is the water in your area? The cold water in Minnesota is much colder than the water in South Carolina. How hard is your water? How dirty are your clothes? What kind of detergent do you use?
Your clothes washer uses three forms of energy to remove dirt from your laundry. Chemical, physical, and thermal energy all work together to bring the dirt on your clothing into solution (the wash water) where it can be rinsed away.
Chemical energy is provided by the water and the soap of your choice. If your water is hard, it already has a lot of minerals in solution and your detergent won’t be as effective.
Physical energy is provided by the movement of the water through and past the fibers of your clothing. With physical energy you don’t necessarily need the particles to be dissolved, sometimes the dirt is just rinsed away (it would settle out of the water if the water were not being swished around)
Finally, thermal energy comes from the temperature of the water in your machine. Particles (soap, dirt etc) are more soluble at higher temperatures. Soluble simply means that the particles can go into solution (in this case, your wash water). If your cold water is particularly cold (around 40°F) your detergent may not even fully dissolve. If your detergent isn’t even in solution, do you think that dirt is going to join it?
All of that basic chemistry will help you as you experiment to find the balance of energy that is good for your wallet (and the environment) and still has the ability to get your clothing clean.
And on a side note, remember that cold water is best for protein type stains (think body fluids and blood) as the stain undergoes a chemical change when heated and is more difficult to remove.
Apparently I’m feeling quite parenthetical today, but I hope it was helpful.
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