The trees must be between 30 to 40 years old for tapping. Even after this long time, the tree is only 12 inches in diameter. A larger tree might get 2, or even 3 taps. From a hook on the tap, the farmer hangs a sap bucket which gathers and holds the sap. A modern version of this is where farmers gather sap into plastic tubing.
Gravity causes the sap to flow downhill to gathering stations for collecting.
Drop by drop the sap flows from the tree during the warm daylight hours until there is enough for the farmers to gather. If we've used buckets, we need to collect the sap regularly, sometimes twice a day. This is a lot of work. It takes many gallons of sap from many trees before the farmers are ready to boil. Each tree produces around 10 gallons of sap per season.