A vaulted basement found at the rabbi's residential house which was oriented according to the requirements of a mikveh has created a controversy in the architectural history of the Ichenhausen Synagogue (Germany). The rabbi's residential house is known to have been built in 1781 during the replacement of the old Synagogue that had existed since 1687. However, the architectural documents concerning the residential house did not contain any information about either the presence or the construction of the mikveh in the basement. Three bricks collected from the northern, eastern and southern walls of the vaulted basement of the rabbi's residence were dated using the thermoluminescence method to find out if the mikveh belongs to the old Synagogue or was built during the construction of the residence. The archaeological dose was assessed using multi-aliquot regenerative and additive dose techniques using quartz extracted from bricks. The age calculations were based on the assessment of annual dose rate in quartz by taking into account the possible variations of water content in bricks. The TL dates of the bricks were found to vary between 1797+/-11 and 1772+/-16 for dry and water saturated environments, respectively. The TL results ruled out the possibility that the walls of the mikveh belong to the former Synagogue.