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.
"Children's clothes, especially their undergarments, tend to carry a lot more things," he said.
Using the right concentration of bleach will kill the bacteria, but using bleach isn't always appropriate, such as when you wash lingerie or colored clothing.
"If you can't use chlorine bleach, you may want to resort to something like Clorox 2 because it has peroxide," said Tierno.
Another option is to periodically clean your washing machine with bleach and water without any clothing in it -- just let the machine go through its regular cycle.
One of the most effective germ-killers is the sun, so scientists say avoid the dryer altogether and let your clothes dry in the sun.
"The ultraviolet radiation kills germs," said Tierno. "It's just as effective as bleach," he added.
But a washing machine is just one of many germ-laden objects that you may encounter in a given day. Handrails, ATM's, refrigerator handles and telephone handsets are among the others.
Gerba added that day care centers and young children's classrooms are also full of germs, as are airplane toilets.
"You've got about 50 people using the same toilet, and it's sometimes hard for people to wash their hands because they don't fit in the sink," he said.
Airplane water also got a thumbs-down from Gerba and Tierno.
"Plane water is very contaminated," said Tierno. "Things aren't cleaned properly, so there's a biofilm on the water."
Despite the huge number of germs you may come into contact with during the day, most of what the ones you'll encounter are harmless.
"Of the more than 60,000 kinds of germs, only one to two percent of them are potentially pathogenic," Tierno said.