Rainwater harvesting is generally allowed for small residential rain barrels in the United States, but the rules are not identical by state. The details can change based on storage volume, roof collection, potable use, plumbing connection, commercial use, new construction, water rights, local ordinances, and HOA rules.
This article is not legal advice. Before installing a large cistern, connecting rainwater indoors, using harvested water as drinking water, or building in a western water-rights state, verify the current rule with your state water agency, health department, building department, or the Department of Energy rainwater harvesting tool.
For setup details, read Best Rain Barrel Setup for Small Gardens. For garden use, see How to Water Plants While Away for 2 Weeks.
Last updated: June 6, 2026.
Quick Answer
Small rain barrels for outdoor irrigation are broadly legal across the United States, but some states regulate storage volume, registration, permitted uses, potable use, or plumbing. Colorado limits ordinary residential rain barrels to two barrels with 110 gallons combined storage. Utah requires registration for rainwater harvesting and allows up to 2,500 gallons with registration. Washington allows rooftop collection without a water-right permit under conditions, but potable use has health and county rules. Oregon allows roof collection but larger tanks and indoor/non-potable systems may involve regulations. Always verify locally.
Rules That Matter Most
| Rule type | Why it matters |
|---|---|
| Small rain barrel | Usually simplest and least regulated |
| Large cistern | More likely to trigger permits |
| Potable use | Health treatment and plumbing rules apply |
| Indoor non-potable use | Building and plumbing codes may apply |
| Western water rights | Some states have specific limits |
| HOA/local ordinance | May affect placement, appearance, or overflow |
| Overflow routing | Can create drainage or neighbor issues |
States That Need Extra Attention
This is a practical verification list, not a complete legal code.
| State | Why to check |
|---|---|
| Colorado | Ordinary rain barrels limited to two barrels and 110 gallons combined storage |
| Utah | Registration required for rainwater harvesting; storage limits apply |
| Washington | Rooftop collection allowed without water-right permit under conditions; potable use differs |
| Oregon | Roof collection is common; larger systems and plumbing may involve rules |
| Texas | Rainwater harvesting is encouraged, but plumbing and large systems have requirements |
| Virginia | Rain barrels are treated differently from regulated rainwater harvesting systems |
| California | Legal, but state/local building and water-quality rules may apply |
| Nevada | Water-rights context makes verification important |
Most other states allow basic residential rain barrels, but local rules still matter.
Colorado
Colorado is the state homeowners most often ask about. Colorado Division of Water Resources states residents can fill and refill two rain barrels with combined storage up to 110 gallons throughout the year. Uses and eligibility can differ for certain well properties and larger systems.
Utah
Utah Division of Water Rights says a person must register rainwater harvesting use, and total allowed storage capacity with registration is no more than 2,500 gallons.
Washington
Washington Department of Ecology says rooftop rainwater can be collected without a water-right permit under current policy if conditions are met, including use on the property where collected and collection from existing structures. Potable use is a separate health and county issue.
Legal Use Is Not the Same as Safe Use
Rain barrel water is not automatically safe for drinking or spraying edible leaves. Roof runoff can contain bacteria, bird droppings, metals, asphalt residue, and other contaminants.
Use garden rainwater more safely by:
- watering at soil level
- avoiding foliar application to leafy greens
- screening barrels
- using overflow safely
- cleaning gutters
- using first-flush diversion when appropriate
FAQ
Is collecting rainwater illegal?
Small residential rain barrels are broadly legal, but state and local rules can restrict storage volume, use, or plumbing connections.
Is there a federal rainwater law?
No single federal law controls ordinary residential rainwater collection. State and local rules matter.
Can I drink rain barrel water?
Not without proper treatment and compliance with health rules. Garden rain barrels are normally non-potable.
Can an HOA ban rain barrels?
HOA rules vary, and some states limit HOA restrictions. Check your covenants and state law.
Related Reading
- Best Rain Barrel Setup for Small Gardens
- How to Water Plants While Away for 2 Weeks
- Low-Water Landscaping Ideas for Hot Yards
Sources
- US Department of Energy: Rainwater Harvesting Regulations Map
- US EPA: Soak Up the Rain, Rain Barrels
- NCSL: Is Catching Rainwater Legal in Your State?
- Colorado Division of Water Resources: Rainwater, Storm Water and Graywater
- Utah Division of Water Rights: Rainwater Harvesting Registration
- Washington Department of Ecology: Rainwater Collection