This’ll work you up into a lather.

Many of the things you thought you were doing right when washing your hands — using hot water, choosing antimicrobial soap — don’t make much of a difference at all. That’s according to a recent study published in the Journal of Food Protection that took a deep dive into hand washing, as well as other recent research.

“The literature on hand washing, while extensive, often contains conflicting data, and key variables are only superficially studied or not studied at all,” the authors wrote of the motivation for their research. “Some hand washing recommendations are made without scientific support, and agreement between recommendations is limited.”

Also see: Why you should stop freaking out about hygiene and let your kids eat dirt

Here are some of the things you may be doing wrong when washing your hands.

  • You don’t lather for long enough. The best way to cut the amount of bacteria on your hands is to lather them for at least 20 seconds — try to sing “Happy Birthday” at least twice to help time yourself — according to the study, which has people wash for five seconds, 10 seconds and 20 seconds. Lather time was the only thing the researchers found that significantly reduced bacteria.Your fellow Americans almost never lather for long enough though: When researchers from Michigan State University watched people washing their hands in public restrooms they found that only 5% washed their hands long enough.
  • You worry too much about the water temperature. Participants washed their hands with water temperatures as high as 100°F and as low as 60°F, the study, which looked at 320 different hand washes and their impact on e.coli elimination. That made no difference on reducing the amount of bacteria on hands.
  • You’re super picky about the type of soap you use. Using an antimicrobial soap, as opposed to just a simple, bland soap won’t make a difference, the study showed. What’s more, this comes on the heels of an FDA ruling about antibacterial soaps: “We have no scientific evidence that they are any better than plain soap and water,” said Janet Woodcock, M.D., director of the FDA’s Center for Drug Evaluation and Research. (Though antimicrobial and antibacterial are often used interchangeably, there is a difference, as Microban notes: “While antibacterial products prevent the development of bacteria, antimicrobial agents such as alcohol-based hand sanitizers prevent the spread of bacteria, fungi, and some viruses.”)

Washing your hands wrong — or not at all — can cost you money. Indeed, the CDC notes that handwashing “is one of the best ways to remove germs, avoid getting sick, and prevent the spread of germs to others” and finds that productivity losses linked to absenteeism cost employers $225.8 billion annually in America, or $1,685 per employee.