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lime treatment, together with chlorination, presents a double line of
protection of the water at the source of supply. If fully maintained
and supervised these methods should limit the risk of water borne
diseases to contamination occurring after the water has left the works.
In order to meet the possibility of the pollution of the water in
reservoirs or mains one of the statutory companies has liberated the
water from the works with a small proportion of free chlorine present
therein. (The other Company has taken similar action during 1939).
Very few complaints and no ill-health have been noted as a result of
the present arrangements.
On the Old Coulsdon Estate considerable anxiety has been felt
from time to time owing to temporary breakdowns of the plant through
broken mains, failure of electric current, and other causes. The new
pump installed last year proved equal to the maintenance of the supply
under normal conditions, but if for any reason the head of water in
the water tower was reduced the system failed to function over certain
parts of the area served, and the consumers were left without water.
For this reason the Council saw fit at the end of the year, after conferences
with the Company, to disapprove further plans for the erection of new
houses until a sufficient and satisfactory supply had been laid on, the
Company meanwhile being encouraged to make alternative arrangements
for the supply of water to the Estate.
Many complaints of the discolouration of water were received,
and bacteriological samples were taken about every fortnight. In
addition, daily samples of the water have been collected and tested
for free chlorine by the Medical Officer of Health. The results of the
latter were very variable, but were of value in ascertaining that this
protective measure was maintained, the question being taken up with
the Company immediately free chlorine was noted to be absent from a
sample.
During the year 23 samples of water were submitted to bacteriological
examination from the Old Coulsdon supply, all of which were reported
upon as being satisfactory.
The statutory maximum limit for hardness in the water supplied
by the East Surrey and Sutton and District Water Companies is 9 degrees,
and 48 samples have been examined by the Department during 1938
to ascertain that this figure was not exceeded.
The results of the most recent chemical examinations are set out
below:—
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