This buried treasure moves slowly beneath our feet through spaces and cracks underground but it is intimately connected to surfacewater. All life depends on this water that can’t be seen. When precipitation falls to Earth, some flows downhill as runoff into a stream, lake or ocean. Some evaporates, and plants take up some. The rest soaks into surface soil and trickles through rocks. This water eventually reaches the water table – the top of a saturated zone of soil or rack, which is called an aquifer.