I was looking closely at a citrus leaf and the entire leaf was laid out so that every part of the leaf was the right size to channel everythying to where it needs to go. A leaf that can fit in the palm of my hand would have made any public works director thrilled if that were his infrastructure.
If you imagine each light spot is a building and the lines are the water and sewer, there would be plenty of redundency and the pipes are perfectly sized.
Below is a closeup picture of a citrus leaf and actual sewer and water maps for a city (available to the public online). I must admit that the sewer lines look more like a leaf but the water lines have the loops.