Yehuda Wiesen asked:
Dear Kollel, Why is it called beit hashoeva?
The Kollel replies:
The Gemara (Sukah 50b) explains that it is based on the verse, "u'She'avtem Mayim b'Sason," alluding to the drawing (She'ivah) of the water for the Nisuch ha'Mayim that is performed on Sukos with great Simchah.
Tosfos there cites the Yerushalmi which says, "From there the people drew Ru'ach ha'Kodesh [by being involved in the Simchah of the Mitzvah]."