VPE 511: Environment and Environmental Hygiene (2+1)

Introduction

BIOLOGICAL EVALUATION OF WATER

• All natural waters, excepting possibly some of the deepset underground waters, are inhabited by a diverse plant and animal life, the chief phyla of the former being Algae, Fungi and Bacteria, whilst the animal kingdom is represented by Protozoa, Sponges, Rotifers, Molluscs, various free-living “worms”, Insects, Fishes and Amphibia.
• The kinds of plants and animals found in any particular water depend largely on the character of the water and on the source from which it is drawn, and, as far as contaminant intestinal bacterial of human or animal origin are concerned, on the degree to which the water has been exposed to sewage and/or manurial pollution.
• In general , the flora and fauna of surface waters are more abundant and more diverse than those of underground waters, whilst those of the deepest subterranean waters are relatively poorer than the life of sub-soil waters.
• A few minute Crustacae feeding on bacteria and fungi are able to live in deep wells and in the subterranean waters on which they draw, but if the wells be of great depth or are poorly aerated the water will usually be devoid of living things.
• Few, if any, of the forms of life, apart from contaminant bacteria of intestinal origin, which may be found in natural waters would appear to be toxic or harmful to man or animals drinking the water.
• In the following paragraphs, some account is given of the more important forms of plant and animal life which are to be found in water supplies, and which may give rise to problems during the purification, storage, and distribution of the water.