Index >> Water Microbiology >> Bacteriological Examination of Domestic Water

Bacteriological Examination of Domestic Water

Natural water supplies such as rivers, lakes, and streams contain sufficient nutrients to support growth of various organisms. Microorganisms enter the water supply in several different ways. In congested centers water supplies get polluted by domestic and industrial wastes, As a potential carrier of pathogenic microorganisms, water can endanger health and life.

From the standpoint of transmitting human diseases, polluting waters with soil, rubbish, industrial wastes, and even animal manure is comparatively harmless. These sources rarely contain pathogens capable of producing human diseases when swallowed with drinking water. Sewage containing human excreta, however, is the most dangerous material that pollutes water.

Theoretically it would be better to examine water for the presence of the specific pathogenic microorganisms. This is also impracticable because of the following reasons:

1. The methods are expensive, tedious, and slow, and by that time the water has already been consumed.

2. The number of pathogenic organisms may be quite small compared to non pathogenic organisms and would be overlooked.

3. Non-pathogenic organisms may interfere with the examination of pathogens.

The direct examination for pathogens, therefore, is not used in routine water analysis. Methods commonly used for the bacteriological examination of water, are based on:

1.The examination of presence or absence of the more common organisms of intestinal or sewage origin.

2.The approximate determination of total numbers of bacteria present in the water sample.