人肉回答：有兩用的水龍頭，多了一個過濾水的出口

Google keyword: "reverse osmosis filter without holes", go to image result, third row second to last picture.  Sometimes you'll have to know what you are looking for before the search. 

 

https://www.kraususa.com/filter-single-handle-commercial-pull-down-kitchen-faucet-in-sfacb.html