Everyone washes their hands, but few keep to “how long”. The US Centers for Disease Control and Prevention says to scrub with soap for at least 20 seconds, and suggests timing it by humming “Happy Birthday” from beginning to end twice. When soap and water are not at hand, hand sanitizer should contain at least 60% alcohol. This sets out the CDC page “About Handwashing”.
1. Wet, lather, scrub 20 seconds, rinse, dry. Five steps.
2. 20 seconds = “Happy Birthday” twice. The CDC’s timing tip.
3. No soap and water? Sanitizer with at least 60% alcohol. Check the label for the alcohol content, the page says.
Five steps — CDC
| Step | What the CDC says | Worth noting (our gloss) |
|---|---|---|
| 1. Wet | Wet hands with clean, running water (warm or cold), turn off the tap and apply soap | Either water temperature is fine |
| 2. Lather | Rub hands together with the soap — backs of hands, between fingers and under nails | Not just the palms |
| 3. Scrub | At least 20 seconds — hum “Happy Birthday” from beginning to end twice | The only step with a set time |
| 4. Rinse | Rinse well under clean, running water | — |
| 5. Dry | Dry with a clean towel or an air dryer | Drying is part of it |
The middle column sets out the CDC step wording; the right column is our gloss.
Key times to wash — the CDC list
- Before, during and after preparing food
- Before and after eating food
- Before and after caring for someone at home who is sick with vomiting or diarrhea
- Before and after treating a cut or wound
- After using the toilet
- After changing diapers or cleaning up a child who has used the toilet
- After blowing your nose, coughing or sneezing
- After touching an animal, animal feed or animal waste
- After handling pet food or pet treats
- After touching garbage
What to watch for when a child vomits or has diarrhea is in vomiting and diarrhea in young children.
When to use hand sanitizer
When soap and water are not readily available, the CDC says to use a hand sanitizer that contains at least 60% alcohol, and to check the product label for the alcohol content. The page puts soap and water first and sanitizer in their place (our reading).
How much difference — CDC “facts and stats”
Another CDC page (“Handwashing Facts”) puts numbers on handwashing education.
| Group | What | Reduced by |
|---|---|---|
| General population | People who get sick with diarrhea | 23 to 40% |
| People with weakened immune systems | Diarrheal illness | 58% |
| General population | Respiratory illnesses such as colds | 16 to 21% |
| Schoolchildren | Absence due to gastrointestinal illness | 29 to 57% |
The same page sets out how germs reach hands — from human or animal feces after using the toilet or changing a diaper, from raw meat carrying invisible traces of animal feces, and from touching objects someone has coughed or sneezed on. The figures are for handwashing education, not the effect of each wash (our reading).
Checklist
- ☐ 20 seconds — “Happy Birthday” twice
- ☐ Before and after preparing food and eating, after the toilet
- ☐ After blowing your nose, coughing or sneezing
- ☐ After pets, pet food or treats, and garbage
- ☐ Sanitizer: check the label for at least 60% alcohol
Questions that remain
How much does handwashing cut infections?
The “About Handwashing” page gives none, but the CDC “Handwashing Facts” page gives the figures in the table above — diarrhea 23 to 40%, respiratory illness such as colds 16 to 21%.
What else in flu season?
Who is eligible for vaccination and when is in flu vaccination.
If you touch a cold sore, the NHS says to wash your hands with soap and water before and after (cold sores).
The NHS says to wash your hands after touching a wart, since they spread through contaminated surfaces and skin contact (warts and verrucas).
To avoid spreading a stomach bug, the NHS says to wash hands with soap and water often and stay off school or work until 2 days after the last bout (diarrhoea and vomiting).
For norovirus, the CDC says you can spread it for 2 weeks or more after feeling better, so wash with soap and water for at least 20 seconds (norovirus).
Sources
- CDC — About Handwashing (Clean Hands) — original (page shows: reviewed 16 February 2024; checked 12 October 2026). 10 key times, five steps and 20 seconds, “Happy Birthday” twice, sanitizer with at least 60% alcohol.
- CDC — Handwashing Facts — original (page shows: reviewed 17 April 2024; checked 12 October 2026). 23 to 40%, 58%, 16 to 21%, 29 to 57%, how germs reach hands.
- Not read. Korean agencies’ handwashing guidance.
- Our additions. The right-hand column of the table.
Where to check further
- The sanitizer label — alcohol content.
Written 12 October 2026. The content sets out the CDC original; the glosses are ours.