Update 5.13.2016: Gov. John Hickenlooper has signed legislation finally legalizing rain barrels. Our original story continues below.
Colorado's ban on collecting rain from residential rooftops has been a contentious topic at the statehouse, and a proposed bill for 2016 means it will likely be debated once again.
"Colorado is the only western state where rain barrels are illegal," said Drew Beckwith, a water policy manager with the nonprofit Western Resource Advocates.
"Every other western state that has our water laws has them legal, and it has not caused the Earth to come crashing to a halt."
So why is there so much controversy over collecting rainwater? The sticking point is whether doing so impacts downstream water users.