In Oregon, all water, including rainwater, belongs to the public under state law. Individuals do not automatically own water flowing through or falling on their property but can obtain usage rights through permits or exemptions.
Water Rights Basics
Oregon follows the prior appropriation doctrine, where water rights are granted “first in time, first in right.” The Oregon Water Resources Department (OWRD) manages allocations to ensure beneficial use without waste, with senior rights prioritized during shortages. Landowners must secure a permit or qualify for an exemption to divert water legally.
Rainwater Ownership
Rainwater is considered public water, but collection from an artificial impervious surface like a rooftop is an exempt use, requiring no permit. Once collected legally, the rainwater belongs to the collector for on-site, typically non-potable uses such as irrigation or gardening. Potable use or collection from non-rooftop surfaces often needs a permit and treatment.
Harvesting Rules
Small-scale rooftop systems (up to 5,000 gallons annually for residences) generally need no water right permit. Larger systems, commercial uses, or those altering runoff may require OWRD approval to avoid interfering with existing rights. Systems must comply with Oregon Plumbing Code for safety, including debris screens and first-flush diverters.
Conservation Focus
Oregon promotes rainwater harvesting for sustainability, reducing stormwater runoff and municipal demand. Incentives like rebates (e.g., Clean River Rewards) support compliant systems. Non-use of rights for five years can lead to forfeiture, emphasizing ongoing beneficial application. For details, contact OWRD at (503) 986-0900.
