There are no state-level restrictions or prohibitions on rainwater collection in California and the state strongly encourages it. No, it’s not illegal to collect rainwater in California. After being in a state of legal limbo, the state has now become actively legal, with the Rainwater Capture Act of 2012, and further tax exemptions in 2018 and a Governor’s executive order in January 2025 which mandates maximum storm water capture throughout the state. There are no permit, capacity or registration requirements for residential use of rainwater in California. California homeowners should be aware of the specific rules and regulations that apply to the use of that water, the types of uses that may need professional licensing, and the local ordinances that may impose additional requirements over and above the state minimum requirements.
Key Takeaways
- It is legal to collect rainwater in California. Rainwater harvesting is encouraged in California and there are no restrictions on collection of rain water for residential use in California under California Water Code Section 10540-10546.
- The Rainwater Capture Act of 2012 allowed the collection of rainwater provided it is done in accordance with the regulations of the State Water Resources Board.
- In 2018, the State of California passed SB-558, which excludes property taxes from the new construction of a rainwater harvesting system.
- In January 2025, Governor Newsom issued an executive order to capture as much storm water as possible, which shows his ongoing and critical emphasis on water conservation.
- In California, rainwater that is collected from your roof is okay. No permit from the state board is necessary. But, if it is collected for landscaping a license would be required. For rain capture systems used to provide a water supply like a swimming pool, hot tub, fountain, or pond, a landscaper needs to have a prime contract for that system.
- Rainwater in California can be used for non-potable uses such as irrigation, landscaping and flushing toilets.
- Certain cities in California have local ordinances that have more requirements than the state requirements.
The Rainwater Capture Act of 2012 made the following changes:
Prior to 2012, the state of California’s laws regarding rainwater collection were confusing and varied from one jurisdiction to the next. The Rainwater Capture Act did away with that ambiguity at the state level.
The Rainwater Capture Act was passed in 2012 which legalizes rainwater collection provided you meet the requirements of the State Water Resources Board. It is okay to collect rainwater from your roof and even encouraged. Doing so reduces demand on streams and reduces water quality problems associated with stormwater runoff, the Water Board states.
The laws of California were amended to encourage rainwater harvesting. Rainwater is a valuable resource for the state. But depending on the size and use of your rainwater system, the rules differ.
The Act is codified at California Water Code Section 10540-10546 and is statewide. It was the legislation that put an end to the local uncertainty and provided a clear direction from the state level for the collection of rainwater for residential and commercial use.
SB-558 is the Property Tax Exemption law for 2018 in California
SB-558 (2018) was passed by the State of California to exempt property taxes for the new construction of a rainwater harvesting system.
This tax deduction is the state’s active financial incentive to homeowners to install rainwater collection systems. California has taken the step of making collection financially desirable by eliminating the property tax liability that would otherwise be imposed on improvements to residential property, whereas states simply allow collection without comment.
This exemption is for new construction of rainwater harvesting systems, and is available to residential and commercial property owners who install qualifying rainwater harvesting infrastructure.
Governor Newsom’s 2025 Executive Order
In January 2025, Governor Newsom signed an Executive Order to maximize storm water capture, further underscoring the importance of water conservation.
This executive order is part of California’s water security issues. California is frequently hit with severe droughts, and storm water collection is becoming a greater part of the state’s water plan. The executive order further cements the legislative framework laid out in the Rainwater Capture Act of 2012 and the tax exemption of 2018, which is a step towards active encouragement of rainwater capture, instead of just permitting it.
Knowing what you can and cannot do in California
To collect the rainwater for outdoor or indoor use, you can put a rain water harvesting system such as a water tank and collect rain water falling on the roof. In California, the only time you would need a permit for rainwater collection is when the rain water collection is being used for a water supply like a swimming pool, spa or fountain.
Rainwater in California is generally only used for non-potable uses such as irrigation, landscape irrigation, and flushing toilets. If you are installing a system, please review local ordinance as some cities may have extra rules.
The actual mechanics of California homeowners is as follows:
Anything else that is usually allowed without a permit:
- Rooftop collection for residential purposes into rain barrels or cisterns.
- Garden/Lawn irrigation with collected water.
- Use for toilet flushing and other non-potable uses indoors.
- Installation of any size cistern system suitable for a practical residential application
- Apply to outside areas for cleaning and car washing.
What needs to be licensed or have extra permits:
- When a rain capture system is used to provide a water supply like a swimming pool, hot tub, fountains, or ponds, a landscaper has to be given a prime contract for the system.
- Water districts may need to be notified if a large-scale commercial or agricultural collection system is used.
- Any use of collected rainwater for drinking or cooking requires proper filtration and treatment per California health guidelines
Local Ordinances: An Additional Layer to Check
For large-scale collection systems, water districts in California, Arizona, and New Mexico are sometimes required to be notified. These rules generally do not apply to rain barrels for residential use.
Even under the relatively loose California state laws, local governments have the power to add on to the state laws. There may be other rules in some cities. A homeowner in Los Angeles, San Francisco, or San Diego should check to see if there are any local ordinance provisions that exceed the state minimum, especially for larger cisterns, or when the cistern is connected to existing plumbing.
There are other considerations with respect to HOA rules. In California, the state that is the most permissive, a homeowners association can still have restrictions on architectural or aesthetic features of visible rain barrels or collection systems. By reviewing HOA governing documents prior to installation, issues of placement, visibility, or system design can be avoided.
Water Quality and Safe Use of Collected Rainwater
Rainwater is usually only used for non-potable uses such as watering lawns, flushing toilets and irrigation.
This use restriction is a valid water quality issue. Rainwater that is collected from the roof surface may contain pollutants from roof material, dust, bird droppings and air pollution. California’s stance on potable use of collected rainwater mandates that rainwater be treated before it is used for drinking, cooking or tooth brushing.
The California State Water Resources Control Board has issued guidelines for rainwater harvesting system design and use, which are the most up-to-date technical standards for residential and commercial systems.
How California is different from other states
California’s role in the nation’s rainwater collection arena is a positive one, neither the strictest nor the laxest.
| State | Legal Status | Volume Limit | Tax Incentive | Key Law |
| California | Legal and encouraged | None | Yes (SB-558, 2018) | Rainwater Capture Act 2012 |
| Florida | Legal | None | No | Riparian rights |
| Texas | Legal and encouraged | None | Yes | Sales tax exemption |
| Arizona | Legal and encouraged | None | Yes | Tax incentives |
| Virginia | Legal and encouraged | None | Yes (tax credit) | State encouragement |
| Tennessee | Legal | None | No | SB 2417/HB 1850 |
| Michigan | Legal | None | No | No restrictions |
| Indiana | Legal | None | No | No restrictions |
| Ohio | Legal | None | No | No restrictions |
| Colorado | Legal with restriction | 110 gallons | No | HB 16-1005 |
| Utah | Legal with restriction | 2,500 gallons | No | Registration required over 100 gal |
California has a solid statutory foundation, a property tax exemption, and a 2025 executive order to collect storm water, making it one of the states which strongly encourages rainwater collection as a public policy.
For California homeowners, here are some useful tips for handling the situation:
When you know these laws, you can avoid fines and keep your system safe and legal.
The following practical steps ensure full compliance with the law and maximum benefit in California by installing a rainwater collection system:
- Check with your local city or county for any other requirements above and beyond the state requirements
- If you are part of a planned community, review your HOA governing documents.
- Ensure that the use, potable or non-potable, has an impact on system design requirements
- Check if your water district provides rebates/incentives in addition to the state property tax exemption
- Make sure your system design meets the requirements of the California State Water Resources Control Board (SWRCB)
- If you have a pool, spa, fountain or pond that will be fed from your system, hire a licensed landscaper to enter into a contract for that piece.
Also Read: Is It Illegal To
Expert and Legal Perspectives
California promotes rainwater collection and does not limit residential rainwater collection in California Water Code 10540-10546. Rain water harvesting is encouraged as a water conservation technique in the state.
Rainwater harvesting is permissible in California under certain conditions and with specific rules and regulations to abide by. Rain water harvesting is encouraged by the State to conserve water, particularly during dry spells.
Rainwater harvesting from the roof is permissible and even encouraged. This will decrease the pressure on the streams and water quality issues caused by stormwater runoff, the Water Board says.
Conclusion
It’s not illegal to collect rainwater in California. There are no statewide regulations in California on rainwater collection, and it is encouraged. The Rainwater Capture Act, 2012, provided the legal framework for the use of rainwater. In 2018, SB-558 made it exempt to tax new residential systems. In January of 2025, Governor Newsom issued an executive order that further bolstered the state’s efforts to capture as much storm water as possible as a water security measure.
No permit is needed and there is no limit on volume for normal residential roof top collection and use for irrigation, flushing toilets and other non-potable uses. Additional professional authorizations will only be required for systems that are intended to provide recreational water, including pools, spas, fountains and ponds, where a licensed landscaper will be the prime contractor.
To ensure that the installation is allowed in the community, California homeowners are advised to check local city ordinances and HOA rules before installation, filter any collected water to be used for drinking or cooking and look into local water district rebates that can be used in addition to the statewide property tax exemption.
To read the national legal framework on rain water collection, check out Is It Illegal to Collect Rainwater?
Frequently Asked Questions
1. Is rainwater collection banned in California?
In California, rainwater collection is perfectly legal and has no permit, capacity or registration requirements for home use.
2. Who is entitled to the water that falls on the roof?
The Rainwater Capture Act of 2012 made it legal to collect rainwater as long as you comply with State Water Resources Board regulations.
3. In California, is there a tax advantage to the rainwater collection?
In 2018, the State of California passed SB-558, which excludes property taxes from the new construction of a rainwater harvesting system.
4. In California, is it safe to drink the collected rainwater?
Rainwater is usually only used for non-potable uses such as irrigation, landscaping and toilet flushing. Collected rain water must be filtered and treated according to California health guidelines.
5. In California, is there a permit required for collecting rainwater?
Harvesting rainwater from your roof is OK in California. A state board permit is not required. However, collecting rainwater for landscaping purposes would require a license. A landscaper needs to have a prime contract in order to enter a rain capture system designed to create a water supply like a swimming pool, hot tub, fountains or ponds.
6. Do any other cities in California have other rain water regulations?
Additional rules may be in effect in some cities. Before installing any rainwater collection system, homeowners should review their local ordinances and governing documents of their homeowners association.
