These two signs were found side by side in a Finnish train bathroom, located next to the water tap. The one on the left has a green background with a white silhouetted hand under a tap and a drop in between. The one one the right has the same tap and droplet silhouette, black on white background, but with a glass underneath and a red slashed circle "no" symbol on top.
The purpose here is of course that the water is only for washing hands, not drinking. But what I found curious was how the drinking was simply implied. Act of drinking is something quite complex to depict, whereas a glass is, at least in this situational context, quite clear. It conveys the message for sure, but I am sort of amused by the fact that if I were to drink from this tab, I probably wouldn't have a vessel with me but rather would drink from the water stream.