With this design I'm trying the show the journey the water takes as it goes through the various cycles, represented by the rings inside the rings. The outer ring shows the water molecules that turn into four visible states of the water: rain (represented by a water droplet), fog (wavy lines), snow (snow flake), and ice (hexagon). These enter the city through the storm sewer system, represented by the next ring, and the city represented by the cogwheel (city line). Next the water leaves the city and flows back into the nature represented by the sphere (earth) and the tree inside (nature). And thus the cycle completes only to begin again.