For the people of Mesopotamia, the month of August-September is for washing the statues of the Goddesses. In mid-month, the Ezem-Inanna-Ka occurs. This is the festival to prepare Inanna for her descent into the Underworld. People wash and consecrate her statues (usually in a river). For Sumer, the month is called “Kin-Inanna” (the work of Inanna), for Babylon, “Ululu” (to purify).
The washing and the re-consecrating the statues of the Gods is a venerable Polytheist tradition. Keeping holy items neat and clean is a duty of piety. Sacred things should always be kept pure. Therefore, cleaning statues, altars, and temples are encouraged at this time.
The statues of Gods have a part of the God residing in them. Therefore, washing the statues and other items of the God is showing reverence to that God. Romans also had ceremonies for washing statues such as Juno on Mothers’ Day (March 1) by matrons.