Jewish law prescribes that both men and women maintain a state of physical purity. Impurity stems from various factors: various illnesses (particularly of the skin), emission of semen, contact with a dead body, as well as the menstrual cycle and childbirth.
To recover the state of integrity, that is, physical purity, total ablution in rainwater or spring water in specially built pools is prescribed. The observant Jew goes to the miqweh, that is, the ritual bath, at least once a week, as well as on those occasions that explicitly require it.
Source: "Gli ebrei questi sconosciuti" by Elena Loewenthal