This section is from the book "A Treatise On Beverages or The Complete Practical Bottler", by Charles Herman Sulz. Also available from Amazon: A Treatise On Beverages.
Fill a clean pint bottle three-fourths full of water to be tested, dissolve a teaspoonful of loaf or granulated sugar, cork the bottle and place it in a warm place for two days. If the water becomes cloudy or milky it is unfit for use. If it remains perfectly clear it is probably safe to use. Bottlers cannot exercise too much care in preparing water for beverage making, and all known tests should be employed to ascertain its purity.