| In the Bible, in Shakespeare, and in your American History classes, mentions of ale, wine and beer are common, and not much ever about the drinking of just plain water. Why? Water and milk-borne diseases were common in those days before pasteurization and knowledge of germs and proper water treatment. Cholera, typhoid, and undulant fever killed many people. Fermented drinks (and some solid foods also!) were found to be safe and consumed by young and old alike. To "stretch" the supply, a little water was often added. But how much of the dangerous water would be safe to add?
|  What to do: Of course, you do not want to use disease bacteria because you would probably make yourself sick. So you want to use bacteria that are non-pathogenic relatives of the common disease bacteria of the Middle Ages. Your school's safe E.coli is a close relative of typhoid, and the dairy bacteria in cheeses and milk are relatives of other pathogens. Thus, stir some E.coli in milk, which already has its own dairy bacteria in it. Immediately divide this up and add various amounts of rubbing ETHYL alcohol to the portions. Then test whether the bacteria has been killed by swabbing some of each onto petri plates containing nutrient agar (for the dairy bacteria), and some detergent agar (for E.coli).
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