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Rainwater harvesting is legal in some form in all 50 states. But the rules are not the same everywhere. Some states give homeowners broad freedom to collect roof runoff. Others limit storage size, where the water may come from, how it may be used, or whether a permit or registration is needed.
This guide is current as of August 31, 2026. State and local rules can change, so use the table below as a starting point and confirm the rules for your property before installing a large cistern, connecting rainwater to household plumbing, or planning to use it as drinking water.
The U.S. Department of Energy notes that state rules vary and that permits may be required in some places. A September 2025 National Conference of State Legislatures overview also found that most states give residents broad freedom to collect rain, while a smaller group places limits on access or use.
Rainwater Harvesting Laws by State
In this table, generally allowed means there is no major statewide household rain-barrel limit highlighted here. It does not mean every installation is exempt from building, plumbing, health, stormwater, zoning, or local permit rules.
| State | Statewide status | What homeowners should know |
|---|---|---|
| Alabama | Generally allowed | Basic roof collection is generally allowed. Check local building and plumbing rules before installing a large tank or connecting rainwater to a building. |
| Alaska | Generally allowed | Household collection is generally allowed. Local requirements may matter for tanks, structures, plumbing, and drinking-water systems. |
| Arizona | Allowed and encouraged | The Arizona Department of Water Resources promotes rainwater harvesting as a way to reduce drinking-water use for landscape irrigation. Systems range from simple drainage to rain barrels and cisterns. |
| Arkansas | Allowed with code requirements | Collection is allowed, but plumbing and public-health requirements can apply when rainwater becomes part of a building water system. Check state and local plumbing officials before indoor use. |
| California | Allowed with specific rules | Simple irrigation systems are allowed. California's onsite nonpotable water regulations became effective April 22, 2026, for certain multifamily, commercial, and mixed-use building systems. Untreated rainwater used only for surface, subsurface, or drip irrigation is excluded from those treatment standards. |
| Colorado | Allowed with strict household limits | Most residences may use up to two rain barrels with a combined capacity of 110 gallons without a water-right permit. Water must come from a qualifying residential roof and be used outdoors on the same property. This exemption does not allow drinking or indoor household use. Some properties with qualifying residential wells have additional collection options. |
| Connecticut | Generally allowed | Basic household collection is generally allowed. Check municipal requirements for larger tanks, plumbing connections, and site drainage. |
| Delaware | Generally allowed | Basic rain barrels and roof collection are generally allowed. Building and plumbing rules may apply to larger or connected systems. |
| Florida | Generally allowed | Household collection is generally allowed. Local governments may regulate tank placement, plumbing, drainage, or construction. |
| Georgia | Allowed with plumbing requirements | Rainwater collection is allowed. Systems connected to building plumbing must follow Georgia's plumbing code and any local permit or inspection requirements. |
| Hawaii | Expressly allowed under 2026 law | Act 209, signed July 8, 2026, requires counties to allow rainwater catchment systems for potable and nonpotable uses on all properties. Counties may still require registration, inspection, or notification. Individual home catchment systems are not regulated by the Hawaii Department of Health in the same way as public water systems. |
| Idaho | Generally allowed; check large projects | Ordinary roof collection is generally treated differently from diversion of natural surface water. Check with the Idaho Department of Water Resources before building a large system that captures or stores water beyond normal rooftop runoff. |
| Illinois | Allowed with plumbing controls | Rainwater may be collected, but nonpotable water must remain separated from the potable water system. Building-connected systems must comply with state and local plumbing rules. |
| Indiana | Generally allowed | Basic rainwater collection is generally allowed. Local plumbing, building, zoning, and health requirements can still apply. |
| Iowa | Generally allowed | Household roof collection is generally allowed. Check local requirements for large tanks and indoor connections. |
| Kansas | Generally allowed | Basic rain barrels and cisterns are generally allowed. Larger or building-connected systems may trigger local codes. |
| Kentucky | Generally allowed | Rainwater collection is generally allowed. Local plumbing and building rules should be checked before indoor reuse. |
| Louisiana | Generally allowed | Basic collection is generally allowed. Local drainage, plumbing, building, and mosquito-control requirements may affect the installation. |
| Maine | Generally allowed | Household collection is generally allowed. Check local codes for large cisterns, buried tanks, and building connections. |
| Maryland | Generally allowed | Basic roof collection is generally allowed. County or municipal stormwater programs may have their own design requirements or incentives. |
| Massachusetts | Generally allowed | Household rainwater collection is generally allowed. Plumbing and health requirements become more important for indoor or drinking-water use. |
| Michigan | Generally allowed | Basic rain barrels and cisterns are generally allowed. Local building and plumbing codes still apply. |
| Minnesota | Allowed with specific plumbing rules | Minnesota's plumbing code specifically covers rainwater catchment systems used for nonpotable applications. A system used only for lawn irrigation is outside that rainwater-catchment chapter, while systems serving indoor fixtures or combined uses must meet the applicable plumbing requirements. |
| Mississippi | Generally allowed | Household roof collection is generally allowed. Check local requirements for larger tanks or building plumbing. |
| Missouri | Generally allowed | Basic rainwater harvesting is generally allowed. Local codes may regulate plumbing, tank placement, or drainage. |
| Montana | Generally allowed | EPA's current Region 8 guidance lists no state rainwater-harvesting permit requirement for Montana. Other building, plumbing, or local rules can still apply. |
| Nebraska | Generally allowed | Household collection is generally allowed. Check local codes before adding large storage or indoor reuse. |
| Nevada | Allowed under a specific exemption | Nevada water law exempts de minimis collection of precipitation from the roof of a single-family dwelling for nonpotable domestic use. Do not assume that exemption covers every commercial, multifamily, potable, or non-rooftop collection project. |
| New Hampshire | Generally allowed | Basic collection is generally allowed. Building, plumbing, health, and local land-use rules may apply to larger systems. |
| New Jersey | Generally allowed | Household collection is generally allowed. Check municipal requirements for tanks, drainage, and plumbing connections. |
| New Mexico | Allowed and commonly used | The New Mexico Office of the State Engineer recognizes household rainwater harvesting for landscape irrigation. Larger commercial projects should be checked with the Water Rights Division, especially where capturing runoff could affect other water interests. |
| New York | Generally allowed | Basic rainwater collection is generally allowed. Local building, plumbing, stormwater, and health rules may apply. |
| North Carolina | Allowed with code requirements | North Carolina's plumbing and residential codes recognize rainwater harvesting systems. Building-connected systems must follow the applicable code provisions and approved rainwater-harvesting standards. |
| North Dakota | Generally allowed | EPA's current Region 8 guidance lists no state rainwater-harvesting permit requirement for North Dakota. Local rules can still apply. |
| Ohio | Allowed; household supply cisterns are regulated | A cistern supplying water for human consumption can fall under Ohio's private-water-system rules. Construction of a private water system requires a local board-of-health permit, and cistern systems can require plans and water sampling. A simple garden rain barrel is a different type of installation. |
| Oklahoma | Generally allowed | Household rainwater harvesting is generally allowed. Check local codes for large storage, plumbing, or structural work. |
| Oregon | Allowed under a water-right exemption | Oregon law exempts the collection and use of precipitation from an artificial impervious surface, such as a roof, from the normal water-right application and permit requirements. Oregon's online 2025 statutes note that parts of Chapter 537 were affected by the 2026 legislative session, so confirm the current text before planning an unusual or large project. |
| Pennsylvania | Generally allowed | Basic roof collection is generally allowed. Local plumbing, building, and stormwater requirements can apply. |
| Rhode Island | Generally allowed | Household collection is generally allowed. Check local plumbing and building requirements for anything beyond a basic outdoor-use system. |
| South Carolina | Generally allowed | Basic rainwater harvesting is generally allowed. Local codes may regulate tank placement, plumbing, and construction. |
| South Dakota | Permit depends on the project | EPA's current Region 8 guidance describes the state rainwater-harvesting permit requirement as situational. Check with the South Dakota Department of Agriculture and Natural Resources before a larger storage or water-use project. |
| Tennessee | Generally allowed | Household roof collection is generally allowed. Local plumbing, building, or health rules can apply. |
| Texas | Allowed and supported by state law | Texas has several laws supporting rainwater harvesting, including protections against some HOA bans. A system connected to a public water supply for potable indoor use has added cross-connection, approval, and licensed-plumber requirements. |
| Utah | Allowed with storage and registration limits | No registration is needed for up to two covered containers when each holds no more than 100 gallons. Larger systems must be registered with the Division of Water Rights, and total storage under the rainwater-harvesting provision is limited to 2,500 gallons. Collection, storage, and use must remain on the same parcel. |
| Vermont | Generally allowed; stormwater rules may apply | Vermont recognizes rainwater harvesting as a stormwater-management practice. Larger regulated projects may have design requirements, while indoor reuse can raise separate plumbing and health questions. |
| Virginia | Allowed under a detailed tier system | Virginia divides uses into four tiers. Tier 1 through Tier 3 systems generally do not need a state construction permit but do require registration. Tier 4 means potable use and requires construction and operation permits. Simple rain barrels used solely for Tier 1 purposes are excluded from the rainwater regulations. |
| Washington | Allowed under state rooftop policy | A state water-right permit is generally not required when rain is collected from an existing structure, the structure has another primary purpose, and the water is used on the property where it was collected. Counties may have separate rules for drinking-water use and new construction. |
| West Virginia | Generally allowed | Basic household collection is generally allowed. Check local codes for larger storage or plumbing connections. |
| Wisconsin | Generally allowed with plumbing controls | Outdoor collection is generally allowed. Indoor or building-connected rainwater systems must meet applicable state and local plumbing requirements. |
| Wyoming | Permit depends on the project | EPA's current Region 8 guidance describes rainwater-harvesting permit requirements as situational. Check with the Wyoming State Engineer before a large or unusual collection project. |
The Law Depends on More Than Whether You Own a Rain Barrel
For most homeowners, a small barrel connected to a gutter is the simplest legal case. The situation changes when the system becomes larger or is tied into a building.
A 55-gallon barrel used to water flowers may face few state requirements. A 2,000-gallon tank supplying toilets, a pump-fed household system, or a buried cistern may involve plumbing permits, backflow protection, electrical work, structural requirements, health-department review, or water-right rules.
That is why a state being listed as "generally allowed" should not be read as "no rules apply."
Outdoor Use Is Usually Simpler Than Indoor Use
Most basic rainwater systems are intended for nonpotable use. Nonpotable means the water is not intended for drinking.
The legal use of captured water also depends on how a rainwater harvesting system works and where it connects to other plumbing.
Garden irrigation is often the least complicated use because the water never enters household plumbing. Once a rainwater line serves toilets, laundry, hose bibs, or other fixtures, plumbing codes may require clear separation between the rainwater system and the potable water supply.
That separation matters. A pump or plumbing error must not be able to push untreated rainwater backward into a public or private drinking-water system. Texas, Minnesota, Virginia, California, and other states have specific rules for building-connected systems.
Drinking Rainwater Is a Separate Question
A law that allows you to collect rainwater does not mean the collected water is automatically safe to drink.
Roof runoff can pick up bird and animal waste, dust, microorganisms, roofing material residues, metals, and other contaminants. Storage conditions can add more risks.
Potable means suitable for drinking under the standards that apply to the water supply. Reaching that point is a whole-system job. It can involve a suitable catchment surface, debris control, prefiltration, treatment matched to the actual hazards, protected storage, correct plumbing, ongoing maintenance, and current laboratory testing.
Hawaii illustrates the difference clearly. Its new 2026 law requires counties to allow catchment systems for both potable and nonpotable uses, but the Hawaii Department of Health still stresses careful system design, maintenance, treatment, and testing for domestic use.
Virginia goes further by classifying drinking-water use as Tier 4 and requiring permits for those systems.
For a household drinking-water system, contact the local health department or other authority that regulates private water supplies before designing the system. A single filter, UV unit, test strip, or home water meter cannot by itself establish that roof runoff is safe to drink.
Large Cisterns Can Trigger Different Rules
Storage size matters in some states.
Colorado's ordinary residential rain-barrel exemption is based on two barrels totaling no more than 110 gallons. Utah allows two containers of up to 100 gallons each without registration but requires registration for larger systems, up to the state's 2,500-gallon limit. Nevada's exemption is tied to de minimis rooftop collection from a single-family dwelling rather than giving every type of rainwater project the same treatment.
A list of US jurisdictions permitting rainwater harvesting is a useful starting point, but local rules can still differ within a state.
Even where the state has no storage cap, a large tank may need structural or site review. Water is heavy. A full above-ground cistern can place a substantial load on its base, deck, or supporting structure. Underground tanks add excavation, soil, groundwater, access, and collapse hazards.
Those issues are separate from the legal right to collect the rain.
Local Rules Can Be Stricter or More Detailed
State law is only one layer.
A county, city, plumbing authority, health department, water utility, or building department may regulate how a system is installed. Local rules can cover setbacks, overflow drainage, tank screening, mosquito protection, backflow devices, pipe identification, permits, inspections, underground tanks, pumps, and connections to public water.
A state law summary should be paired with the permit requirements for rainwater harvesting that may apply to a specific installation.
Washington, for example, generally exempts qualifying rooftop collection from the state water-right permit requirement, but the Department of Ecology tells homeowners considering rainwater as a primary drinking-water source for new construction to check with their county.
Hawaii's 2026 law likewise requires counties to allow catchment systems while still permitting counties to require registration, inspection, or notification.
How to Check the Rules Before You Build
Before buying or installing a system, check it in this order:
- Define the use. Decide whether the rainwater will irrigate a garden, supply outdoor hose connections, flush toilets, serve other indoor fixtures, or be considered for drinking.
- Check your state's water agency. This is especially important in Western states where water rights can affect collection.
- Check your city or county. Ask the building or plumbing department whether the tank, pump, buried piping, or indoor connection needs a permit.
- Contact the health authority for potable use. Do this before designing a drinking-water system, not after the tank has been installed.
- Check utility and backflow requirements. This is essential if rainwater piping and public water are present in the same building.
- Check property restrictions. HOA rules, easements, historic-district rules, and zoning requirements can affect where equipment may be placed even when state law allows collection.
The Department of Energy also recommends checking both state regulations and local permit requirements during system planning.
Frequently Asked Questions
Is it illegal to collect rainwater in any U.S. state?
There is no blanket statewide ban on ordinary rooftop rainwater collection in the 50 states as of August 31, 2026. However, several states control the amount, source, intended use, registration, or permitting. Local rules can add more requirements.
Which states have the strictest rainwater harvesting rules?
Colorado and Utah have some of the clearest household storage limits. Nevada provides a specific exemption for de minimis rooftop collection from single-family homes for nonpotable domestic use. South Dakota and Wyoming have situations where state water permits may be relevant. The exact answer also depends on the size and intended use of the system.
Do I need a permit for a basic rain barrel?
Often, no. A small barrel used for outdoor irrigation usually has fewer requirements than a cistern or plumbing-connected system. Colorado specifically allows qualifying residential systems totaling up to 110 gallons without a state water permit, and Utah allows two covered containers of up to 100 gallons each without registration. Always check local rules as well.
Can I use harvested rainwater inside my house?
Sometimes. Indoor use can trigger plumbing, treatment, cross-connection, backflow, permit, and inspection requirements even when outdoor irrigation is broadly allowed. Check the plumbing authority before connecting rainwater to toilets, laundry, or other fixtures.
Can I legally drink collected rainwater?
Some jurisdictions allow rainwater to be used as a potable supply if the system meets their requirements. Others restrict or closely regulate that use. Legal permission does not establish water safety. Drinking-water systems need appropriate collection, treatment, current laboratory testing, maintenance, and compliance with the health and plumbing requirements that apply locally.
Can an HOA stop me from installing a rain barrel?
That depends on state law and the governing documents. Texas, for example, limits an HOA's ability to prohibit rainwater-harvesting installations, although reasonable appearance or screening rules may still apply. In other states, check both state protections and your HOA documents before installing a visible tank.
Do large rainwater tanks have different legal requirements?
They can. Larger tanks are more likely to raise building, structural, zoning, excavation, plumbing, overflow, or water-right questions. Utah also has a specific statewide storage limit, while Colorado's standard residential rain-barrel exemption is limited by storage capacity. Check the applicable authorities before installing a large cistern.
