Ladies What's with the Gargling?

The bathroom hand washing situation in the office is outside my comfort zone. There is thin soap that doesn't require water to get it sudsy, and most people don't bother to use it (None of the Japanese homes I have visited have even had soap in the bathroom). After rinsing their hands many ladies splash some water in their mouths, gargle and spit, this seams to be repeated a few times to achieve a satisfactory result, whatever than may be.