An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »


WaterSense Specification for Weather-Based Irrigation Controllers

The performance criteria contained in this specification are designed to test the capability of the controller to provide adequate and efficient irrigation while minimizing potential runoff when the controller is programmed and operated in compliance with the manufacturer's instructions. Conformance with these requirements is an indication that the controller has the capacity to modify or generate appropriate irrigation schedules based on weather inputs. 

You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.