For most clothing the hotter the water, the cleaner the clothing will be. This is a general rule but works out to be true for most of the clothing you'll encounter.
When to Use Hot Water
Most linens and white clothing are washed in hot water to remove germs and heavy soil. However, many of our clothes will not come out looking very nice if they are washed in hot water. Hot water tends to make some clothing shrink, wrinkle, and fade.
Different colors may turn out splotchy after using hot water. Other fabrics are delicate and don't respond well to high temperatures.
When to Use Warm Water
For most people, the majority of their laundry is washed with warm water. Warm water is actually exactly what it sounds like, a mix of hot and cold. Some machines mix the hot and cold water 50-50, although many newer machines mix 60-40. Warm water is usually the best choice for permanent press and jeans. It allows good cleaning action without as much fading, wrinkling, and shrinking.
When to Use Cold Water
Cold water is usually used for delicate items or items with instructions to be washed in cold water. It's also the best options for clothing that have bright colors that may run or fade at higher temperatures. If your cold water items are heavily soiled or dirty, you need to be especially diligent about checking and pre-treating for stains.
You may also have to wash the items for longer or allow them to soak before washing if they are heavily soiled.
4 Ways to Choose the Right Washing Temperature
1. Check the Tag
While you will be able to use your discretion with many clothing items, checking the tag allows you to find any special instructions.
We often forget to check the tag when we buy items, only to find out there is a 25 step list of washing instruction for best results. Check the tags and pull out items that have special instructions, especially if it is an item that you really want to take care of.
2. Check the Water Temperature on Your Washing Machine Before You Wash
Use a candy thermometer and check the water temperature of the cold, warm, and hot water coming out of your machine. Hot water is most often 10 degrees colder when it arrives at your machine from when it leaves your hot water heater. In general, hot water is 130 F (54.4 C) or above. Warm water is between 110 and 90 F (43.3-32.2 C). Cold water is generally between 80 and 60 F (26.7-15 C). If cold water is below 60 F (15 C), clothes are unlikely to be cleaned very well. The temperature of your water can vary greatly depending on the weather outside, too. Be aware of what is actually coming out of your hoses and into your washing machine.
3. Pre-Treat Stains
Pre-treating the stains will allow the clothing to get clean even if it needs to be washed with warm or cold water. Although cold water isn't always the best for getting out stains, a cold water soak can be a lifesaver for certain types of fabrics that have a stain on them.
Be patient. We want our clothes to come out clean and undamaged. Sometimes cold water is the answer for that. Take the time to pre-treat for stain removal before they are washed and you have a much better chance of clothing coming out clean and stain-free.
If clothing does require cold water, try soaking the clothing before washing to ensure that clothing will actually be cleaned thoroughly. A soak can be anywhere from a few minutes to overnight. The tougher the stain, the longer the soak will need to be. Be patient. Really good things can come from a little time spent soaking.