Banned Nationwide? The Truth About America's Rainwater Laws

Few water myths are as persistent — or as instructive — as the claim that collecting rain off your own roof is a federal crime. The truth is far more nuanced and fascinating.

The origin of the myth lies in the American West's 'prior appropriation' water doctrine, enshrined in Colorado's 1876 Constitution. Under this 'first in time, first in right' framework, all water — including rainwater that might eventually flow into streams — was legally considered a public resource allocated to existing rights holders. For over a century, that meant even capturing a barrel of rain in Colorado was technically illegal if it could deprive a downstream senior water rights holder.

By the 2000s, Colorado was the last state where this remained a near-total prohibition. Internet listicles and viral social media posts began circulating the story — but stripped away the geographic specificity, turning a Western-states regulatory quirk into an alleged national ban. The 'illegal rainwater' myth spread widely and stuck.

Colorado began loosening restrictions in 2009 (SB 09-080, for rural residents with exempt wells) and finally passed House Bill 16-1005 in 2016, signed by Governor Hickenlooper, allowing all residential homeowners up to two 55-gallon barrels. The state had actually commissioned a Colorado State University study confirming that small-scale residential collection had negligible impact on downstream water rights before passing the law.

Meanwhile, the rest of the country tells a very different story. Texas is arguably the most rainwater-friendly state in the nation — state law prohibits HOAs from banning collection systems and exempts rainwater harvesting equipment from sales tax. Arizona requires new commercial buildings to incorporate rainwater systems for irrigation. New Mexico mandates rainwater systems in new construction in some municipalities and offers city rebates. Florida passed a 2019 law forbidding local governments from banning residential collection.

The 'illegal everywhere' claim is a myth. But Colorado and Utah's restrictions are entirely real — and their historical roots in frontier-era water law make for a genuinely weird and instructive story.