I leave here this video that will make you think twice about take water from the tap, assuming you don't have a purifying filter. Well, that will at first, but then have to discover tiny forms of life that we rarely stop to think about, for one simple reason: We do not see. And for us if we don't see, is not there. But it is a wrong way to see the world, because there really are thousands of things around us interacting with everything we touch. In this case, small freshwater inhabitants:
Microscopic Worlds - Life that we don't see from Daniel Stoupin on Vimeo.