Hot water is used to finish the job. Hot water cleans best because it speeds up the chemical reaction between the detergent and the water. This means that it takes less time to wash and less detergent. When you wash your clothes in hot water, they will smell clean and fresh the next day.
Gebhardt says that a lot of people think that hot water cleans fabrics. In reality, the water is not hot enough unless it has a “sanitize” cycle. Even though drying in the sun is just as good as using a dryer, only the dryer can sterilize. Sanitation is also only needed when dirty clothes have harmful microorganisms on them, like vomit from being sick or feces on cloth diapers. Gebhardt says to use hot water in this situation.
Even though they use less water, modern top-loading washers with a central agitator clean much better than those made 15 or more years ago. Manufacturers have slowly lowered wash temperatures to meet the strict energy limits set by the Department of Energy for how much hot water can be used. Energy Star says that a washer uses about 90% of the energy it needs to heat the water. This means that the less hot water is used, the more energy is saved.
By washing clothes in both hot and cold water, you can get rid of any dirt that is still stuck in them. But because some detergents don’t dissolve well in water below 15°C, you’ll need to use more detergent if the water is cold.
It doesn’t matter if you wash your clothes in hot or cold water because the temperature of the water has nothing to do with color loss. No matter how hot or cold the water is, colors can be washed. If your clothes get too hot or tumble around in the dryer, they might fade. Normal wear and tear on things can cause colors to fade over time.