Collecting rainwater in Wyoming is legal for personal outdoor use, and the state has no dedicated permit process for residential rain barrels. The catch is that Wyoming’s constitution declares all water within the state to be public property, which creates a legal gray area once a collection system grows large enough to affect downstream users. For a homeowner with a barrel under a downspout, that gray area is theoretical. For a rancher planning a 10,000-gallon cistern off a barn roof, it is not.
Why Wyoming Treats Water Differently
Article 8, Section 1 of the Wyoming Constitution states that the water of all natural streams, springs, lakes, and other collections of still water within state boundaries is “the property of the state.”1Wyoming Secretary of State. Constitution of the State of Wyoming That language is broader than what most state constitutions contain, and it puts the State Engineer’s Office in charge of how water gets allocated.
Wyoming allocates water under the prior appropriation doctrine, often summarized as “first in time, first in right.” Whoever first puts water to a recognized beneficial use holds a senior right, and later users take junior positions. When supply tightens, senior rights get filled first and junior users can be shut off entirely.2Wyoming State Engineer’s Office. Wyoming State Engineer’s Office That framework shapes every water question in the state, including rainwater.
What You Can Do Without a Permit
Wyoming has no statute specifically addressing residential rainwater collection. Nothing explicitly authorizes it and nothing explicitly bans it. The State Engineer’s Office has not created a permit category for rain barrels or small residential cisterns, and in practice small-scale collection for personal outdoor use happens across the state without paperwork.
The City of Laramie’s official FAQ puts the practical picture bluntly: “At this time the state does not have a permit process and there is no City of Laramie ordinance preventing the use of rain barrels. Citizens are able to catch storm water for personal use without regulation.”3City of Laramie. Frequently Asked Questions That reflects how the rest of the state operates as well. Homeowners connect barrels to downspouts, water their gardens, and never file anything.
The absence of a specific permit process is not the same as an open door. The constitutional framework still applies, and the State Engineer’s Office retains authority over water appropriation. What it means in practice is that small residential collection sits below the regulatory threshold, while anything larger can draw scrutiny under existing water rights law.
Where the Line Gets Blurry
The gray area matters when your collection system grows. Wyoming law requires anyone who wants to appropriate state water to obtain a permit from the State Engineer’s Office.4University of Wyoming. Wyoming Water Law: A Summary A homeowner catching a few hundred gallons off a roof for tomatoes is not going to trip that wire. A rancher installing a 10,000-gallon cistern system fed by barn rooftops is another matter, because that volume can realistically reduce runoff that feeds a stream where someone else holds a senior right.
If your system is large enough that it could reduce flow reaching a senior right holder’s diversion point, you are on shaky legal ground without a permit. That is where real enforcement risk lives, not with backyard barrels.
Commercial and Agricultural Collection
Farms, ranches, and commercial operations face more scrutiny. Large roof areas on barns, warehouses, or other structures collect substantial volumes that would otherwise reach the local watershed. Before approving any appropriation, the State Engineer’s Office evaluates whether it would injure existing downstream right holders.
Agricultural applicants typically need more extensive documentation, including maps that show the catchment surface, storage location, and the land where collected water will be applied. The mapping helps the State Engineer decide whether senior rights downstream would be affected. If you operate a commercial property and want to install a large-scale system, the safest step is to contact the State Engineer’s Office before building anything.2Wyoming State Engineer’s Office. Wyoming State Engineer’s Office
How the Permit Process Works
If your project is large enough to require a permit, you file through the State Engineer’s Office using a surface water application form. Form SW-1 handles new diversions, including ditches, pipelines, and water hauls, with a $50 filing fee. Reservoir-type storage under 20 acre-feet uses Form SW-3A at $25. Stock-only reservoirs under 20 acre-feet use Form SW-4, also at $25.5Wyoming State Engineer’s Office. Surface Water Applications and Forms
The application asks for a legal description of the property (township, range, and section numbers), the location and type of catchment surface, the storage capacity of your tanks or cisterns, and a clear statement of how you plan to use the water. The office reviews whether granting the permit would injure existing right holders. Expect several months. Standard filing fees are set by regulation, generally $50, with some smaller special-application permits at $25.6Legal Information Institute. Wyoming Code of Regulations 037-1 Section 1-3 – Surface Water Fees
Penalties for Unauthorized Diversion
Enforcement against backyard rain barrels is essentially nonexistent, but Wyoming does have teeth for larger unauthorized diversions. Violating the state’s water appropriation laws is a misdemeanor. After written notice from the State Engineer’s Office or Board of Control, each day of continued noncompliance counts as a separate offense, punishable by a fine of up to $1,250 per day. Failure to comply with a written order can add up to three months in jail on top of the daily fines.7Wyoming Legislature. Wyoming Statutes Title 41 – Water
In practice, these penalties target significant diversions from streams or unpermitted wells and reservoirs, not a 55-gallon barrel under a downspout. The statutory authority still exists, which is why anyone planning a large system should not skip permitting.
Using Collected Rainwater Safely
For most Wyoming residents, the setup is straightforward: a barrel or cistern connected to a roof downspout, with the water used for gardening, landscaping, or washing outdoor equipment. Keep the system modest, use the water outdoors for non-potable purposes, and you are operating within the practical bounds of how the state handles residential collection.
Drinking the water is a different question. Potable use falls under the Wyoming Department of Environmental Quality rather than the State Engineer’s Office. Rainwater intended for household drinking needs filtration and disinfection to meet safe drinking water standards, and you should contact the department for specific guidance before relying on harvested rain as a household supply.
Label any storage tanks and outdoor taps connected to a rainwater system as non-potable, particularly if your property has both municipal plumbing and a harvested rainwater line. Keeping the two systems clearly separated and marked prevents cross-contamination and protects anyone who visits.