Collecting rainwater in Colorado is legal for most households, but the state caps how much you can store and limits what you can do with it. If you live in a single-family home, duplex, townhome, or multi-family building with four or fewer units, you can keep up to 110 gallons across no more than two rain barrels, and the water can only be used outdoors.1Justia Law. Colorado Revised Statutes Title 37, Article 96.5, Section 37-96.5-103
The 110-Gallon, Two-Barrel Rule
No permit is needed for a qualifying household to use two rain barrels totaling 110 gallons or less. You can fill and refill those barrels as often as you like throughout the year. The 110 gallons is a storage cap, not an annual quota.1Justia Law. Colorado Revised Statutes Title 37, Article 96.5, Section 37-96.5-103
The water has to come from a rooftop downspout on a building used primarily as your residence. Runoff from a driveway, a detached shed, or a commercial building does not qualify. The barrels must stay on the property where the rain fell.2Division of Water Resources. Rainwater, Storm Water and Graywater
What the Water Can Be Used For
Collected rainwater is restricted to outdoor, non-potable uses. Watering the lawn, irrigating flower beds, and tending a garden all qualify. Drinking, cooking, bathing, and other indoor household uses are prohibited.1Justia Law. Colorado Revised Statutes Title 37, Article 96.5, Section 37-96.5-103
Vegetable gardens are allowed because garden irrigation is an outdoor use. Rooftop runoff can carry bird droppings, dust, and residue from roofing materials, so the practical approach is to water at the base of plants rather than overhead, especially for anything you plan to eat raw.
Can an HOA Ban Rain Barrels
No. Colorado law bars homeowners’ associations from prohibiting rain barrels outright. An HOA can still set reasonable rules about placement and appearance, but a flat ban is not enforceable.
Larger Collection With a Well Permit
Properties served by an exempt residential well or a small-capacity well, and not connected to a municipal system serving more than three homes, can collect more than 110 gallons. That requires a Rooftop Precipitation Collection System Permit from the Colorado Division of Water Resources before collection begins.2Division of Water Resources. Rainwater, Storm Water and Graywater
Permitted uses track your existing well permit. If the well permit covers indoor household use and livestock watering, the collected rainwater can be put to those uses as well. If the well permit is limited to irrigation, so is the rainwater. Collection still has to come from the rooftop of your primary residence.3U.S. Environmental Protection Agency. Summary of Colorado’s Water Reuse Guidelines or Regulations for Consumption by Livestock, Landscaping and Onsite Non-potable Water Reuse
This is the only route in Colorado where rainwater can legally be used indoors, and it only works for rural properties that meet the well permit criteria. Homes served by a municipal tap or a shared well supplying more than three dwellings do not qualify.2Division of Water Resources. Rainwater, Storm Water and Graywater
What Happens If You Break the Rules
Colorado does not set a fine schedule for homeowners who exceed 110 gallons or use rain barrel water indoors. Enforcement runs through the water rights system instead. The State Engineer can curtail individual rain barrel use when a downstream water rights holder shows that the barrels are interfering with water they are legally entitled to receive.1Justia Law. Colorado Revised Statutes Title 37, Article 96.5, Section 37-96.5-103
In practice, the risk is tied to impact. Two barrels behind a suburban home are unlikely to attract attention. Storing hundreds of gallons without a well permit in a water-scarce area with active downstream rights is a different matter, and senior rights holders have strong legal standing to protect their allocations.
Keeping Barrels Safe and Usable
Standing water breeds mosquitoes, and an uncovered barrel can become a neighborhood problem within days. Cover every opening with fine mesh screen, including the downspout intake and any overflow ports. Leave an air gap between the downspout and the barrel so water passes through the screen rather than around it.
Use the water promptly. Stagnant water encourages algae that can clog the spigot and create odors. If mosquito larvae appear, drain the barrel and scrub the interior with warm soapy water to remove eggs stuck to the walls. Check screens and seals for wear, especially after winter.
Placement matters too. Put barrels on a flat, stable surface near a downspout, slightly elevated if you can, so gravity helps when you attach a hose. Keep them out of direct sunlight when practical, since heat speeds algae growth and degrades plastic over time.