THE BACTERIOLOGICAL INVESTIGATIONS 
UNDERTAKEN FOR THE WATER COMMITTEE 
OF THE CITY OF LIVERPOOL* 
In November, 1897, arrangements were made with Professor Boyce, M.B., University 
College Liverpool, to undertake systematic examinations of the bacteria in the Liverpool waters, 
and special investigations of the sources of supply. 
Report of Professor Boyce 
The bacteriological analysis of water is universally regarded as furnishing us with the most 
delicate means of ascertaining the purity of a water supply. By its means we are enabled to 
state : — 
1. That pathogenic bacteria, such as the organisms of typhoid and cholera, are absent. 
2. That the water is free from those organisms which are found in the alimentary canal 
of man and animals, such as the Bacillus coli and the Bacillus enteriditis sporogenes, 
organisms which would strongly tend to indicate sewage contamination. 
3. That the sand filters work efficiently and retain the greater proportion of the bacteria 
present in the unfiltered water. 
The bacteriological analysis is of two kinds : — 
a. Quantitative. /'. Qualitative. 
Quantitative analyses determine the number of bacteria present in a cubic centimetre of 
water. It is found in practice that when the number of micro-organisms is small (under 100) the 
chances of pathogenic organisms or organisms indicating sewage contamination being present is 
very remote. In order, however, to definitely determine the presence or absence of pathogenic 
organisms a qualitative analysis is made. 
Qualitative Analyses 
These are made with special media and under special conditions of incubation, in order to 
favour the growth of the particular organisms it is desired to find to the exclusion of other 
bacteria. Two organisms which are regularly sought for in this way are the Bacillus coli and 
the Bacillus enteriditis sporogenes. In addition to these occasional examination is made for 
thermophilic bacteria. This curious class of organisms grows at a very high temperature — 
between 50° and 70° C. — at temperatures, therefore, which readily kill ordinary putrefactive and 
pathogenic bacilli. From time to time various species of bacteria are isolated and cultivated and 
propagated in the laboratory, and it has been found that certain species are common in unfiltered 
and rare in filtered water. The sand of the filter bed has its special organisms, and sometimes 
from the dead end of pipes almost pure cultivations of one particular species can be found. The 
* Reprinted from the ' Report of the Water Engineer.' 
