Dirty Laundry? How Nasty Germs Survive in Your Washer

May 27, 2010 -- Your dirty laundry may actually be even dirtier after you wash it. That's because experts say washing machines are teeming with bacteria that find their way onto your clothes -- and then onto you.

Our smallest items -- our undergarments -- are the biggest culprits because of the presence of fecal matter and the different types of bacteria it can carry.

Charles Gerba, a professor of microbiology at the University of Arizona, has done extensive research on the germs that fester in our washing machines.

"If you wash a load of just underwear, there will be about 100 million E. coli in the wash water, and they can be transmitted to the next load of laundry," Gerba said.

"There's about a tenth of a gram of poop in the average pair of underwear," he added.

Fecal matter can carry a number of different germs, including the hepatitis A virus, norovirus, rotavirus, salmonella and E. coli.

Philip Tierno, a professor of microbiology and pathology at the New York University School of Medicine and author of the book, "The Secret Life of Germs," said bacteria from the skin, such as staphylococcus, can be found on clothing and towels.

You may have been relying on your detergent to get rid of all the dirt and germs, but if you're not using bleach or very hot water, you're not killing the bacteria -- they're getting on your hands and staying in the washing machine.

"Most of the hot water people use is not hot enough. You need water that's between 140 and 150 degrees to kill germs," said Tierno.

If you're using cold water, Gerba recommends washing your hands after you handle wet clothes, especially if you're washing children's clothes.