Beneficial use is a legal concept requiring that water rights holders put allocated water to a recognized productive purpose, such as irrigation, municipal supply, or industrial use. Water not put to beneficial use may be subject to forfeiture.
Beneficial use is a foundational principle of water law, particularly under the prior appropriation doctrine, requiring that water diverted from a natural source be applied to a recognized, productive purpose. Examples of beneficial uses include domestic and municipal water supply, agricultural irrigation, livestock watering, industrial processing, mining, power generation, recreation, fish and wildlife habitat, and aesthetic enjoyment. The specific uses recognized as beneficial vary by state, and many jurisdictions have expanded their definitions over time to include environmental and instream flows. Under prior appropriation, the right to use water is contingent upon putting it to beneficial use without waste; failure to use an allocated quantity can result in partial or total forfeiture of the water right through abandonment or nonuse provisions. The concept of beneficial use also limits the quantity a right holder can divert to the amount reasonably needed for the stated purpose, preventing hoarding or speculative holding of water rights. Debates over what constitutes beneficial use and what constitutes waste are increasingly common as societies reconsider traditional allocations in light of growing environmental awareness, climate change, and competing demands. Some jurisdictions are recognizing environmental flows and groundwater recharge as beneficial uses, reflecting evolving societal values.