While most medical authorities condemn the use of water high in solids, the ideal drinking water is neither soft water nor distilled water--that is, water that is perfectly free from any saltiness--but one that contains a moderate amount of the ordinary constituents of the earth. It is reasonably safe to assume that any unpolluted water containing as high percentage of solids as 1000 parts of total solids to the million, and that is agreeable to the taste, would be safe for drinking. “Chemical analysis in general indicates the possible pollution of water. A relatively high content of organic substances, nitrate, chlorides and sulphates, might indicate contamination, particularly when ammonia is also present. On the other hand, a high content of just one of the above-mentioned substances, be it organic, chloride, nitrate or sulphate, may originate from the natural soil strata.” =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). =Ammonia.=--In the analysis of water the presence of ammonia is an indicator of organic matter. Ammonia is not of itself injurious but it indicates the presence of matter in which bacteria find conditions suited to their growth. Free ammonia is usually considered an indicator of recent pollution, while albuminoid ammonia indicates the presence of nitrogenous matter that has not undergone sufficient decomposition to form ammonia compounds.