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?
Signed,
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:
- Chemical
- Physical
- Thermal
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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Send your questions to helpme@home-ec101.com.
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.
Click the image below to get hundreds of tips and tricks to make laundry less of a pain in the butt.
I use cold water for almost all my laundry. I do use liquid detergent to avoid the dissolving issue. The one thing that does not come out well in cold water is grease so if I know that there are items with grease spots I do use warm water for that load.
@JoyceK oil has to be completely surrounded by detergent to come into solution. It’s the old oil and water do not mix thing. Heat also reduces the viscosity of the oil making this easier.
I always wsh in cold except for sheets & kitchen towels. I also have very hard water. I don’t have any problems getitng my clothes clean, every once in a while I need to rewash an item to get a spot out but that is usually when I miss it the first time and don’t pre-treat. I do use liquid detergent.
I really really wish I could start washing our clothes in cold water simply for the cost savings – but ever since I was little I’ve always had this mental block when it comes to cold water from the tap in my mind it has always equated to being “dirty” – so all of our clothes get washed in warm and our sheets, comforters & towels get washed in hot water to kill germs – I also skip the fabric softner and use vinegar as it works wonders especially for towels!!!
I researched this myself for my blog, and while warm/hot water does CLEAN better it will not kill germs. Household water does not get hot enough to kill them- especially if you have small children and your water heater is set to the recommended 120 degrees. For example, to kill e. coli, temps must reach 160F (72C). However, dryers DO get that hot, bleach will kill germs, or drying in the sun (UV).
@Milehimama logically I know this is correct, I’ve known it for years – it’s a complete mental block on my part 😛
One of my favorite things about you and your blog is that you don’t just give an answer, you give the background for the answer. It’s fascinating how much you know. LOVE it. Thanks for being awesome.
I always wash with cold water. That’s how my mom did it and her mom before her. In fact, not until I read your post did I even consider that there was a choice. Love your thorough explanation. Thanks, Heather!
Heather,
Seriously you just rocked my world. I do not come here nearly enough. I bow to you. This has been a huge question for me. Since I live in SoCal, I’m thinking I could do more cold water. My question is: We do all of our towels and sheets in hot water to kill bacteria. Is that necessary?
@FashOrganized No. As Milehimama says below, the water does not get hot enough to actualy kill the bacteria. To kill germs you need to use bleach or the dryer will get hot enough to kill bacteria.
Oh, I have one of those grost-out stories… I learned when I lived in Florida that to get stains out of kids’ clothes, especially milk, I had to use cold water and oxyclean. I’ve just kept up that habit when I moved here to Colorado. And, we have small children so the water was turned down low.Well, (get to the point already!) after the recent post here about cleaning out your washer, I decided to do it. This was a week or so after we turned up the heat on the water heater because the kids are getting old enough to be smart about it. I got a good amount of black gunk out of the washer. Not long after that, I found more gunk around the top, and started pulling it out. I got way more gunk the second time, coming out in big pieces. Long term, I’ve had my washer about ten years. BLECH.So yeah, cold water is good, but you might end up with more gunk in the washer basin over time.
I’m so glad you said “it depends” instead of adding to my warm water guilt! Maybe our clothes are dirtier than normal (I do have teenage boys!) or maybe our water is too hard or too cold, but I have tried using cold water and a wide variety of laundry detergents (including homemade) and my laundry just does NOT smell clean. In fact, it smelled really disgusting like it hadn’t been washed at all. Going back to warm water has made all the difference. It’s worth a try, but not worth a giant guilt trip if it doesn’t work for you.
we have no choice but to use cold or room temperature water where we currently live. and to top it off, it is outrageously hard water!! so…. i dissolve my liquid soap. i use something akin to ivory for the laundry. while i the states i discovered it under the name zote and i think iris… have i digressed??
i dry EVERYTHING in the sun. and yes, on occasion i use softener though i prefer vinegar as a rinse. the sun does WONDERS!! and our items smell great! and no, they aren’t even stiff as they were where we used to live and i’d air dry. maybe it’s because we are close to the beach and the breeze is better…?
I realize that this is an old post but I only found this site today. So ok, even hot water won’t kill germs. But is it necessary to kill them? Doesn’t the detergent release the surface tension so that they can be *washed* away by the water? I never use bleach or antibacterial soaps but I occasionally add some tea tree essential oil to my sheets and towels for its powerful antimicrobial action. I air dry to save electricity and also because I don’t do any work that Nature will do for me!