This drinking water faucet has a single standard 1/4" compression fitting at the base which allows it to hook to virtually any standard water treatment system. Fits: Ametek Reverse Osmosis Systems American Plumber Reverse Osmosis Systems US Filter Reverse Osmosis Systems Culligan Reverse Osmosis Systems Pentek Reverse Osmosis Systems And many, many others... This unit has a 3" shank and is NSF listed and certified to NSF/ANSI Standard 61 section 9.