Disinfecting towels is the fastest way to make them clean and usable, but it's not enough to throw them in the laundry with a bit of detergent. In most cases, disinfecting towels -- or any laundry -- requires the use of a natural or synthetic disinfecting agent.
If you need to disinfect towels -- for example, if you or someone in your home has been sick and towels have been contaminated with bodily fluids -- fill your washing machine with hot water and about 3/4 cup of bleach. Wash white towels on a normal cycle.
Wash contaminated colored towels susceptible to bleach discoloration in water heated to 160 degrees Fahrenheit for about 30 minutes, according to the website Eco Nuts; hot water disinfects fabric and kills germs.
Colloquially speaking, you might say your towels need disinfecting, but they most likely don't if they're just plain old dirty. You can add mild disinfecting substances such as vinegar, hydrogen peroxide, tea-tree oil and lemon juice to white laundry to get towels a little extra clean.
Hanging towels on the line to dry in the hot sun also disinfects them.