Rainwater harvesting is the capture, diversion and storage of rainwater. For most water sources in Oregon, users must obtain a water right in advance from the Oregon Water Resources Department. However, rainwater can provide a unique exemption to this rule and a viable alternative or backup water source for Oregonians. It’s important to understand the nuances of this exemption to make sure the method of harvesting rainwater in storage tanks or cisterns will qualify and to understand other permits or reviews that may be required. This document answers frequently asked questions regarding state and local regulations for collecting and storing rainwater in a tank or cistern. Regulations for storing captured runoff in ponds or reservoirs are different and are not addressed here.
Do I need a water right to harvest rainwater from a roof and store it in a tank or cistern?
No. As long as the water does not come in contact with the soil at any time from harvest to storage, the collection of precipitation water from an artificial impervious surface into a tank or cistern does not require a water right from the Oregon Water Resources Department. For more information, refer to Water Rights in Oregon and ORS 537.141.
Do I need a building permit to build a rainwater harvesting system?
This depends. Systems with larger storage tanks (such as those greater than 5,000 gallons) are more likely to require a building permit from your local building official. This will also depend on site-specific conditions, such as the slope of the land and its relationship to other structures. It’s a good idea to check with your county and city building and planning officials to learn more about local permit requirements and land use ordinances that may apply to your rainwater harvesting system.
Do I need a plumbing permit to build a rainwater harvesting system for potable water?
Yes. In addition, the system should be designed by a registered or licensed design professional. Your city or county building officials will issue plumbing permits and can also refer you to design professionals in your area. Refer to Oregon Plumbing Specialty Code Appendix K: Potable Rainwater Catchment Systems.
Do I need a plumbing permit to build a rainwater harvesting system for non-potable water that will connect to plumbing inside a building or structure?
Yes. If the system is used for in-home applications, such as flushing toilets or washing clothes, whereby system components, pipings or fittings connect to plumbing or drainage inside a building or structure, a plumbing permit is required. In addition, the system should be designed by a plumbing contractor or registered design professional. Refer to the Oregon Plumbing Specialty Code Chapter 16: Non-potable Rainwater Catchment Systems.
Do I need a plumbing permit to build a rainwater harvesting system for non-potable water that does not connect to plumbing inside a building or structure?
No. If the system does not require plumbing or drainage inside a building or structure, whereby all system components, pipings and fittings are on the exterior of the building, and rainwater is used only for non-potable uses such as irrigation, you do not need a plumbing permit. In addition, the system does not need to be designed by a plumbing contractor or registered design professional. Refer to Oregon Plumbing Specialty Code Chapter 1: Administration.
Do I need an electrical permit to install electrical equipment to power my rainwater harvesting system?
Yes. If permanent facilities are installed to power your system, electrical permits are required. This does not apply to mobile plug-in equipment. Your city or county building officials will issue electrical permits.
What process should I follow to ensure my rainwater harvesting system complies with state and local regulations?
Once you have an idea of the scope and scale of your rainwater harvesting system, follow these steps.
- Contact your OWRD district watermaster and city and county building and planning officials to understand legal requirements for your rainwater harvesting system.
- Design your project. Below are several resources that you may find helpful in this process.
- Oregon Department of Consumer and Business Services: Oregon Smart Guide: Rainwater Harvesting. This includes information about the fundamentals of rainwater harvesting and is a good place to start when first considering system design.
- Federal Energy Management Program: Rainwater Harvesting Calculator, Rainwater Harvesting Map Tool and Rainwater Harvesting Technology Review. These are tools and resources to help understand rainfall collection potential and other system design considerations.
- American Rainwater Catchment Systems Association educational videos. These are detailed videos of the ARCSA Rainwater Harvesting Manual.
- Oregon State University Extension: Harvesting Rainwater for Use in the Garden. This includes information on harvesting rainwater specifically for irrigation on small-acreage properties.
- Acquire any required permits or review.
- Construct your system and stay in contact with permitting officials if the scope or infrastructure change.
- Schedule a site visit with your district watermaster to inspect final construction and receive a letter of exempt use.
