Abstract: A tap for the tanks of automatic liquid-filling machines includes a cylindrical cursor housed in a cylindrical sleeve located on the bottom of the tank. A tube is inserted in the lower part of the cursor, and a central shaft extends therethrough to openings for the air exhaust. The cylindrical cursor can slide vertically and is blocked in different positions as defined by impressions present on the cylindrical surface of the cursor which receive a blocking pin. With this adjustment the placing of the tap on containers of different heights is facilitated without it being necessary to vary the distance between the tank and the containers to be filled.