system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is harvesting rain water illegal.

Been hearing for this for a while, why is it illegal?
gpt
Okay typical harvesting of rainwater usually isn't illegal. Whats illegal is trapping large amounts of water on your land. So you cant go and build an artificial lake to catch all the rain on your property. This is because in many places farms depend on the water that would have run off your property into streams. Simple rain barrels arent illegal, giant water storage like diverting streams etc is.