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and from six shallow wells (in gravel and sand) two at the Old
Deer Park, two at Petersham and two at Ham.
The water from the deep well, Old Deer Park and Petersham
Wells is pumped to a low level reservoir at Petersham where it is
mixed before distribution. If flooding occurs, as occasionally
happens, the wells in the flooded area are shut down for a time.
Samples are taken frequently for analysis, generally after the
water has been treated (i.e. as it is supplied to the Public) but
occasionally—for purposes of comparison—before treatment.
Routine samples are taken monthly and other samples taken
when it is considered necessary, for instance, after flooding.
Bacteriological examinations are made more frequently than
chemical analyses for it is the presence or absence of certain
bacteria which indicates pollution.
The Bacteriologists ascertain and report on, among other
things, the absence or presence of certain excretal organisms in
varying quantities of water.
Almost invariably the reports on the Richmond Water before
it has been treated are very good. No Bacillus Coli in 100 cubic
centimetres and no other excretal organisms. Occasionally a
sample has been taken which, before treatment, has been found to
contain Bacillus Coli in 100 cubic centimetres, but none in 50
cubic centimetres or less. No other excretal bacteria have ever
been found in any reports with which I have had to deal.
Bacillus Coli is very wide spread. It is found in all rivers and
in excreta of animals as well as in that of man. The presence of
such bacteria might be due to accidental contamination of the
vessel in which the water is placed at the time of collection.