Here is an interesting story about the revival in contemporary Judaism of the Mikveh, the ritual bath that goes back to Biblical times. Even today someone converting to Judaism must be immersed in the water. It was also used to deal with various kinds of “uncleanness.” Today, Jews are using it more therapeutically, to deal with times of transition, to symbolize new beginnings, etc.
For a Christian, of course, the Mikveh speaks to us of Baptism. I’d like to see some scholarship relating the ordinary Mikveh–and apparently most houses of that time had a pool for this–and the Baptism of John and then of the Church.