Is It Illegal to Collect Rainwater in the US? The Truth Is Complicated

The rumor that collecting rainwater is universally illegal in the United States spread primarily because of Colorado's uniquely strict historical laws — and because outdated or imprecise articles describing those laws went viral online. Colorado's restrictions stem from the Doctrine of Prior Appropriation, a 19th-century western water law principle meaning 'first in time, first in right.' Under this doctrine, water rights are allocated to whoever historically claimed them first — including water that falls as rain, which was legally treated as part of the downstream watershed. This meant that before 2016, an average Colorado homeowner technically needed a water rights permit to collect any rainwater at all, since intercepting it could theoretically deprive downstream senior rights holders of their allocation.

Colorado began loosening these rules with Senate Bill 09-080 (2009), which allowed rural residents on exempt wells to collect some rainwater with a permit. Then, in 2016, House Bill 16-1005 opened residential collection to almost all homeowners — but capped it at two rain barrels and 110 gallons total, for outdoor use only. Research commissioned by the state showed that household-scale rain barrels have negligible impact on downstream water users, helping pave the way for the change.

The viral myth that collection is 'illegal everywhere' likely exploded from news coverage of Colorado's pre-2016 laws, articles about the 110-gallon cap that omitted context, and 'weird laws' listicle sites recycling inaccurate claims. In reality, much of the country — including Texas, Arizona, New Mexico, and Florida — not only permits rainwater harvesting but actively incentivizes it through tax credits, rebates, and mandates that new buildings include collection systems. The U.S. Department of Energy even maintains an interactive state-by-state regulatory map promoting the practice for federal facilities.