Dear Home Ec 101,
I read that I should wash clothes in cold water when doing laundry to save energy. However, I was taught to wash everything in warm water. Can my socks, toddler clothes, and my husband’s workout clothes get truly clean using cold water?
Tepid in Topeka
When I first launched this site in 2007, I had no clue how often I would use my chemistry background.
There isn’t a simple yes or no answer to this question.
I know “Can I use cold water to wash clothes” sounds like a simple question, but there are several factors in play.
If you prefer to watch a video response to the question, it’s after the text.
How cold is the water you’ll use to wash your clothes is the biggest factor to consider.
For example, the cold water in Minnesota is much colder than the water in South Carolina. Most detergents don’t work well in water under 40ºF.
In the newest washing machines, they mix cold and hot water, to keep the cold water at a standard 60ºF – 80ºF. If your washer uses straight from the tap cold, you need to be aware.
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:
These three forms of energy unite like the wonder
twins triplets work together to bring the dirt on your clothing into the wash water, which acts as the solution where the filth is rinsed away.
Chemical energy is provided by the water and the soap of your choice. If your water is hard, it already has lots of minerals in solution, which will cause your detergent to not 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.
If you use tap cold water to wash your clothes, there may be very little thermal energy to help clean your clothes.
Particles (soap, dirt etc.) are more soluble at higher temperatures. Soluble means that the particles can go into solution (in this case, your wash water). If your cold water is particularly cold, which detergent makers say is 40°F or less, your powdered detergent may not even fully dissolve.
How cold is 40°F? It’s right around where you set your refrigerator, so it’s pretty chilly.
If your detergent isn’t in solution, do you think that dirt will join it?
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 cool (not hot, but certainly warmer than 40ºF) water is best for protein-type stains (think body fluids and blood) as the stain undergoes a chemical change when heated and making those stains much more difficult to remove.
Many modern washers have a setting called tap cold and cold. When you set to tap cold, this uses the cold straight from your tap, instead of mixing in hot to keep it between 60º and 80ºF. If you are in a colder climates, this may not ever be a good choice. If you are in a very warm climate, you may not need to ever use the cold option.
Apparently, I’m feeling quite parenthetical today, but I hope the information was helpful.
Remember, science is our friend when it comes to cleaning. It’s the unexpected chemistry that can be a disaster. To avoid those experiments, please check out our series: Home-Ec101.com’s Guide to Household Chemicals.
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And here is the promised video version of the post. I’m working on getting over my fear of being on camera. Bear with me.
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