Organic Matter.
—Organic matter may come from peat swamps, decaying leaves and grasses; or it may come from decayed animal matter which finds its way into the soil; or worst of all it may come from cesspools or other sewage. While the presence of organic matter does not necessarily indicate the presence of disease-producing bacteria, it is a medium in which such germs live and multiply; for that reason it is an indicator of possible harm.
“Waters containing a high percentage of organic substances and among them products of putrefaction are frequently used without damage but they are capable of producing gastro-intestinal catarrh, phenomena of excitement and paralysis as well as death. Of the many pathogenic bacteria that sooner or later may get into the water, those of cholera and typhoid are of special importance.
“Pathogenic bacteria occur but rarely and when once they find their way into a water, they generally do not multiply but remain for a greater or lesser period viable.
“Bacteria enter wells by three different modes: first, from surface water that is washed from the soil by rain; second, from faulty construction of the curbing; and third, from bacteria entering the soil from vaults, etc.” (Van Es).