system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why would it be illegal to collect rain in barrels?
gpt
"Rainwater harvesting is not illegal.  It was heavily restricted in Colorado, Washington and Utah until 2009, but all three states have since relaxed their bans.  In six or seven other states, rainwater harvesting is regulated -- you have to obtain a permit, which is in most cases is about making certain that your harvesting equipment doesn't contaminate groundwater -- but not illegal.  (You have to obtain permits to construct houses or drive automobiles, but that doesn't make people claim such activities are "illegal.")
The guy in Colorado who was jailed for 30 days in 2012 had been denied his permit, but went ahead and built three giant reservoirs anyway -- in other words, his real offence was defying the state regulatory agency.
Anyway.  The theory behind regulation of rainwater harvesting is simple: water falling from the sky is public property, not private property, and belongs in the water table where it can restore diminished streams and reservoirs.  Those who collect it privately are "hoarding" it.  Of course the opposite theory is: a person who uses rainwater first is consuming less public water.
The Internet, not being subject to any kind of screening or editing, is a great place to plant and spread misinformation for political purposes.  Re-read any of those "rainwater collecting is illegal" articles and you'll note the political spin, which is a first hint that the article is exaggerated." 

Found this after a quick Google search.