If you pour water into a typical hand sanitizer, which is typically alcohol-based, the water will generally dilute the sanitizer and reduce its effectiveness.
Hand sanitizers are designed to kill or deactivate harmful microorganisms, such as bacteria and viruses, on the skin. They typically contain a high concentration of alcohol (usually ethyl or isopropyl alcohol) as the active ingredient. Alcohol acts as a disinfectant by denaturing proteins and disrupting the cell membranes of microorganisms.
When you add water to hand sanitizer, it dilutes the alcohol content, which reduces its ability to kill microorganisms effectively. The sanitizer may become less potent and lose its ability to provide the desired level of protection against germs.
It's worth noting that hand sanitizers are usually formulated to be waterless, allowing for rapid evaporation and leaving behind the active disinfecting agents. Adding water can interfere with this quick evaporation process, making the sanitizer less effective and potentially leaving a residue on the hands.
If you need to use a hand sanitizer, it is generally recommended to follow the manufacturer's instructions and use it as intended, without adding any additional substances like water. Additionally, hand sanitizers should contain at least 60% alcohol to be effective against many common pathogens.