Canon XXX
None of the priesthood, nor clerics [of lower rank] nor ascetics, nor any Christian or layman, shall wash in a bath with women; for this is the greatest reproach among the heathen.
It is an abomination to bathe with women.
This canon was renewed by the Synod in Trullo, canon lxxvij.
Zonaras explains that the bathers were entirely nude and hence arose the objection which was also felt by the heathen.
This canon is found in the Corpus Juris Canonici, Gratian’s Decretum, Pars I., Dist. LXXXI, c. xxviij.