Today we collected over three litres of birch sap in just a few hours from two taps that we fitted this morning. To be honest, it just tasted of slightly sweet water, but it is very refreshing.
We drilled about 15 cm into the tree at an angle of approx 30 degrees. The pipe is pushed about 2-3 cm into the hole and the sap starts flowing immediately but slows down to about four drops per second after a while. We taped the bottles to the tree to prevent them falling over when full. It probably took about 4-5 hours to fill each bottle. We left the tubes in situ but plugged them. I'll collect some more later in the week.
The sap keeps for 2-3 days in the fridge. Apparently it takes around 90-120 litres of sap to make one litre of syrup (whereas maple syrup only needs 30:1).