Hand-washing has been a hot topic now.  So here's a question:  Do you really need soap?  And does washing with just water even do anything?

The answer is, it's better than nothing.  But most people don't really understand the science behind how soap works.  Here's why it's so much better than just water.

There are two essential ingredients in most soap:  Vegetable or animal fat.  And lye, also known as sodium hydroxide.

Instead of killing germs, soap removes them from your hands.  And it's VERY good at it.

That's because germs tend to stick to the oil and grease on our skin.  And water alone won't get rid of that oil, because they don't mix.  But soap likes both oil and water.

Soap molecules have one end that wants to bind with water, and another end that wants to bind with oil.  So they can get in between and bind with both at the same time.

In other words, soap sticks to the oil molecules where all the germs are, and allows the water to wash them off.  Which is why it really is worth the extra few seconds to use soap, because it does a much better job.

Now you know.

Live Science