New York Codes, Rules and Regulations
Title 1 - DEPARTMENT OF AGRICULTURE AND MARKETS
Chapter VI - Food Control
Subchapter E - Retail Food Stores (Article 19 Agriculture and Markets Law)
Part 271 - Retail Food Store Sanitation Regulations
Subpart 271-6 - Sanitary Facilities and Controls
Section 271-6.8 - Backflow

The potable water system shall be installed to preclude the possibility of backflow. Devices shall be installed to protect against backflow and backsiphonage at all fixtures and equipment where an air gap at least twice the diameter of the water system inlet is not provided between the water supply inlet and the fixtures flood level rim. No hose shall be attached to a faucet that is not equipped with a backflow prevention device.