Thank you for your question, steve10047! Your Delta Faucet pull-out spout incorporates a backflow protection system that has been tested to be in compliance with ASME A112.18.3 and ASME A112.18.1 / CSA B125.1. It incorporates two certified check valves in series, which operate independently and are integral, non-serviceable parts of the wand assembly. This information can be found on page 7 of the installation manual.
Best regards, Edward
Date published: 2018-06-30