As I walked home from the University today, I saw a man shoveling the sidewalk. He was shoveling a puddle.
The entire sidewalk was covered with a thin layer of water, but a sizeable amount had collected on the sidewalk outside his building, and he was scooping it up and throwing it on the street. Not only was the man contributing to what has probably become a very icy intersection at this time of night, but he was engaged in a fairly tedious task. Sure, there's water pooled in front of your building, but there's some all over the rest of the sidewalk, too: when you shovel some away, water from somewhere else is going to flow back in. Essentially, the man was lowering the water level of the entire block, one millimeter at a time.