This is one of several mikva'ot (ritual baths) found
at the site. They were water-proofed with hydraulic plaster. The Mishnah notes the importance of immersion in water for spiritual purification
and lists the requirements for such ritual baths.
The ritual baths were fed by water from the aqueduct. Mikva'ot similar
to those at Qumran were typical of public and private buildings in Jerusalem
and elsewhere in the Second Temple period.