Can you collect rainwater in Colorado?
Yes, you can collect rainwater in Colorado, but the situation is more restrictive than in many other states. Colorado has a complex history with water rights under the prior appropriation doctrine, which historically treated virtually all precipitation as belonging to the system of water rights.
The Historical Context
Colorado operates under the prior appropriation doctrine — first in time, first in right. This system was developed during the gold rush era to allocate water from rivers and streams. Because the doctrine treats virtually all precipitation as belonging to water rights holders, rainwater harvesting was traditionally viewed as an illegal diversion. For many years, Colorado was one of the most restrictive states for rainwater collection.
The 2016 Law Changes
House Bill 16-1005, passed in 2016, significantly relaxed restrictions. The law created two pathways for legal rainwater collection. First, properties with a permitted well can collect rainwater from their rooftop for use on the same property. Second, a residential pilot program allows households without wells to collect rainwater under specific conditions. The system must be registered with the state.
The Residential Pilot Program
The pilot program allows households in certain areas to collect rainwater from rooftops for outdoor uses. The property must be served by a participating municipal water provider. The system must include at least two rain barrels with combined capacity of no more than 110 gallons (approximately 415 litres). Collected water may only be used for outdoor purposes. Participants must register their system with the state.
Getting Started in Colorado
If you have a permitted well, register your rainwater harvesting system with the Division of Water Resources. If you do not have a well, check whether your water provider participates in the pilot program — most major Front Range providers are participants. Purchase barrels with secure lids, mosquito screens, and overflow outlets. While Colorado's rules are more restrictive than elsewhere, the legal collection of rainwater is now possible, and the trend is toward further liberalisation.
Advocacy and Future Outlook
Colorado's rainwater harvesting laws continue to evolve. Advocacy groups such as the Colorado Water Congress and local conservation organisations are pushing for further liberalisation of rainwater harvesting restrictions. Proposed legislation has sought to increase the 110-gallon limit for non-well properties and expand the pilot program statewide. Public support for rainwater harvesting has grown significantly, reflecting increased awareness of water conservation needs and the desire for individual action on environmental issues. As climate change intensifies drought conditions in the western United States, pressure to allow more widespread rainwater harvesting is likely to increase. Colorado residents interested in rainwater harvesting should stay informed about legislative developments and consider participating in the policy process by contacting their state representatives.
Comparative Context
Compared to other states, Colorado's approach to rainwater harvesting remains among the most restrictive in the United States, despite the 2016 liberalisation. Most states have no restrictions at all, and many actively encourage rainwater harvesting through incentives and technical support. The historical reasons for Colorado's restrictive approach — rooted in 19th-century mining water rights — are increasingly seen as outdated in the context of modern water management challenges. The contrast between Colorado's cautious approach and the proactive support in states like Texas, Florida, and California highlights the diversity of water law frameworks across the US. For Colorado residents, the key message is that rainwater harvesting is now legal and accessible, even if the current framework is more limited than in many other states.