How long should I wash my hands?

Recently, a friend of mine asked me, “Do I really need to spend 30 seconds washing my hands?”

The answer is, not necessary 30 seconds, but you need to scrub for longer than you probably feel like.

The Centers for Disease Control (CDC) recommends scrubbing your hands for at least 20 seconds. But where does this advice come from?

This blog post will answer that question and delve into the why and when of handwashing, explaining how proper handwashing technique can significantly reduce your risk of getting sick and protect those around you. We’ll also explore some fun ways to make handwashing a habit, especially for kids! So, keep reading to learn how to keep yourself and your loved ones healthy with the power of soap and water!

Why is Handwashing So Important?

Washing your hands is one of the simplest and most effective ways to prevent the spread of germs and illnesses. Germs like bacteria and viruses can live on our hands for hours and easily transfer to our eyes, nose, and mouth when we touch our faces. This can lead to a variety of infections, including the common cold, flu, and gastrointestinal illnesses.

Proper handwashing with soap and water can significantly reduce the number of germs on your hands and help protect yourself and others from getting sick.

Make it a Habit: When to Wash Your Hands Throughout the Day

Handwashing is especially important during these times to help prevent the spread of germs:

• Before, during, and after preparing food. This includes handling raw meat, poultry, and seafood, and preparing fruits and vegetables.
• Before eating. Germs can transfer from your hands to your food and make you sick.
• After using the toilet. Always wash your hands after using the bathroom, even if you don’t use the stall.
• After blowing your nose, coughing, or sneezing. Germs from your respiratory system can spread to your hands when you cough or sneeze.
• After touching animals. Animals can carry microbes that are harmful to humans. Wash your hands after petting animals, cleaning up after them, or handling animal food.
• After touching garbage. Germs can thrive in trash cans, so wash your hands after taking out the trash.
• Before and after visiting someone who is sick. This can help prevent you from getting sick and from spreading germs to others.
• After being in a public place. Germs are often present on surfaces in public places like doorknobs, shopping carts, and elevator buttons.

By making handwashing a habit during these key times, you can significantly reduce your risk of getting sick and spreading germs to others.

Why scrub for 20 seconds?

CDC website states, “Nonetheless, evidence suggests that washing hands for about 15-30 seconds removes more germs from hands than washing for shorter periods.”

So, I was curious, what are these studies that the CDC website cites to reach this conclusion?

The studies that support the 20 second scrub

1. A literature review article that discusses 2 studies on this topic:

-A paper from 1964 in the British Medical Journal showed that hand washing with bar soap and running water for 30 seconds reduced bacteria significantly compared to unwashed hands.

-A study demonstrated that 30 seconds of washing is better than 15 seconds at reducing bacteria on hands. But they found that there was not a huge difference between 15 and 30 seconds of washing. Although the difference was significant, the review article states that “in everyday practice the difference is not meaningful.” When discussing this study, the review article cites the Campden BRI Guidelines, which you have to purchase. So, it is not clear to me when the study was conducted and if it was published.

2. A paper from 2008 in the journal Applied Environmental Microbiology, showed that there is not a significant difference in the reduction of bacteria when people washed their hands for 15 and 30 seconds, especially when not using antimicrobial soap.

3. An abstract from a conference presentation in 2012—which was later published in the Journal of Food Protection in 2015—showed a greater reduction of bacteria on hands washed for 20 seconds compared to 5 seconds.

A note about study #3

First of all, study #3, cited on the CDC website, is a presentation abstract, not a peer-reviewed publication. It’s important to cite peer-reviewed publications because they have been subjected to more scrutiny—the process of peer-review. Therefore, peer-reviewed studies can be trusted more than non-peer-reviewed studies.

My second issue is that the peer-reviewed paper shows a different result than the presentation abstract: the difference between the 5 and 20 second washes was not as large as the presentation abstract stated. It’s possible that they made different comparisons in the publication than they did in the presentation abstract. But it is impossible to know for sure, because conference abstracts provide few details.

The other studies (#1-2 above) still support the act of hand washing for at least 15 seconds, so I am not going to disagree with the CDC’s recommendation of 20 seconds. But I would prefer that that the CDC cited peer-reviewed publications to support their recommendations.

Hand washing recommendations around the world

For interest’s sake, I looked up the hand washing duration recommended by a few different countries.

Recommended hand washing times in different countries:
United States (CDC) – 20 s
United Kingdom – 20 s
New Zealand – 20 s
Ireland – 15 s
Canada – 20 s
Australia – 15-20 s

So, how long should you wash your hands?

Wash your hands for 20 seconds.

How to Time Your Handwashing (Fun Methods!)

The CDC and lots of articles/websites recommend singing the Happy Birthday song twice. I hope you all sing it proudly out loud (I mean, why not?). I timed this and it’s pretty accurate. I tried to figure out who I could give credit to for thinking to tell people to sing Happy Birthday twice, but I couldn’t find anything. So, if you can figure it out, let me know in the comments below! I’ll post about it and give you credit for finding it!

For me, though, honestly, I think singing Happy Birthday TWICE every time I wash my hands sounds horrible. I think this clip from the Woody Allen film “Whatever Works” says it all.

So, do what you like: sing Happy Birthday twice, sing 20 seconds of your favorite song, or just count to 20. I prefer counting. But please, wash your hands.

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Want to take your kids on a hands-on exploration of the microscopic world? Be sure to grab my ebook, ‘Joyful Microbiology Activities,’ which has 10 fun and simple microbiology activities you can do at home or in the classroom!

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