Washing your hands with only water does not kill germs, but it does physically remove a significant portion of them. In one controlled study, rinsing with water alone reduced bacterial contamination from 44% to 23%, cutting the presence of bacteria on hands roughly in half. Soap and water performed better, bringing that number down to 8%. So water-only washing helps, but it’s not a substitute for soap when soap is available.
How Water Removes Germs Without Killing Them
Neither plain soap nor water actually kills most germs on your hands. What both do is remove them mechanically. Running water loosens dirt and microorganisms from the skin’s surface, and the physical motion of rubbing your hands together helps dislodge them. The rinse then carries those loosened particles down the drain.
Soap adds a chemical advantage: its surfactants act like tiny magnets that grab onto oils, dirt, and microbes that cling to your skin. Your hands are naturally coated in oils, and many germs sit embedded in that oily layer. Water alone can’t dissolve oil effectively, which is why a water-only rinse leaves behind a larger share of contamination. Soap lifts that oily layer off the skin and suspends the germs in water so they wash away. The CDC notes that people also tend to scrub more thoroughly when using soap, which adds a secondary mechanical benefit.
How Much Better Is Soap?
The gap between water-only and soap-and-water washing is real but varies depending on what you’re trying to remove. For bacteria, soap clearly wins. In a study where volunteers contaminated their hands with fecal bacteria, water alone left 23% of samples still positive for bacteria. Soap and water dropped that to 8%. For one specific type of gut bacteria (Enterococcus), the difference was even more dramatic: 15% of samples remained positive after water-only washing versus just 3% with soap.
For viruses, the picture is more nuanced. A study testing both enveloped viruses (the type with a fatty outer shell, like influenza and coronaviruses) and non-enveloped viruses (hardier types without that shell) found that washing with water only for 20 seconds produced germ removal rates statistically similar to soap and water for both virus types. The researchers found no significant difference between the methods. This suggests that for viruses, the mechanical action of rubbing and rinsing may matter more than the soap itself.
That said, this was a controlled lab study. In real-world conditions, where hands may be visibly soiled, greasy, or heavily contaminated, soap’s ability to cut through oils likely provides a more consistent and reliable clean.
Water Temperature Does Not Matter
If you’ve ever cranked the faucet to hot thinking it would help kill germs, the evidence says otherwise. Multiple studies have tested hand washing at temperatures ranging from about 40°F to 130°F and found no difference in how many germs were removed. This held true with both plain soap and antibacterial soap.
The reason is simple math. Common bacteria like E. coli and Salmonella survive at temperatures up to 131°F for over ten minutes. Staph bacteria need 50-plus minutes at 140°F to be eliminated. Water hot enough to kill these organisms in a reasonable time frame would cause severe burns within seconds. A 2013 review concluded that warm water should not be recommended for its germ-killing properties, a position echoed by the World Health Organization.
Cold water works just as well as warm water for hand washing. Use whatever temperature is comfortable.
When Water Alone Is Your Best Option
If you’re somewhere without soap, washing with water is still worth doing. Reducing bacterial contamination by roughly half is a meaningful improvement over not washing at all, especially before eating or after using the bathroom. The key is to wash thoroughly: rub all surfaces of your hands, including between your fingers and under your nails, for at least 20 seconds under running water.
Duration matters more for some germs than others. Research found that cutting wash time short had no effect on removal of enveloped viruses but did reduce the removal of non-enveloped viruses. So if water is all you have, a longer, more vigorous scrub partially compensates for the lack of soap.
What About Hand Sanitizer?
Alcohol-based hand sanitizer is often suggested as a backup when soap and water aren’t available. It works well against enveloped viruses (the category that includes flu and COVID), but lab testing shows it is not effective against non-enveloped viruses like norovirus. Water-only washing, by contrast, showed similar removal rates for both virus types. So in situations where norovirus or similar hardy pathogens are a concern, even a water-only rinse may outperform hand sanitizer.
For everyday use, soap and water remains the gold standard. Antibacterial soap offers no additional benefit for consumers over regular plain soap, according to the CDC. The surfactant action of any soap, combined with 20 seconds of rubbing and rinsing, is the most reliable way to get your hands clean.