3 day rations

[Caius Fabius]

In The Healing Hand : Man and Wound in the Ancient World, [amazon]Man and Wound in the Ancient World[/amazon] the author (Guido Manjo, MD) shows research that the vinegar killed bacteria, and the alcohol in wine kills bacteria, and that another chemical compound in wine kills bacteria, therefore "posca" is an excellent way to make most water have less bacteria. This book is an excellent read, even if you don't plan to re-enact a medicus, just because it helps you understand the various schools of medical thought in the time period we study.