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37
In addition to the above, 162 routine colometric tests for
checking the efficiency of purification plants were also made by the
Inspectors. The chlorine content and pH value are checked by
means of a Lovibond Comparator.
VERMINOUS CONDITIONS AND UNCLEANLINESS
One hundred and thirty-nine visits to premises by the
Inspectors related to eradication of bugs, dirty conditions and
disinfestations.
Twenty-eight nuisances were found and 35 remedied during
the year. (This latter figure includes those found in 1955 and
abated in 1956).
WATER SUPPLY.
Twelve samples of drinking water were taken during the year,
to ascertain the toxic metal content (zinc). In no sample was zinc
detected.
The supply of water to the Borough is provided by the
Metropolitan Water Board, and I am indebted to the Director of
Water Examination, to that authority, for the following information
on the supply during the year 1956 :—
The supply to the Borough of Bromley is from four of the
Board's Kent Wells, namely, North Orpington, Orpington, Shortlands
and West Wickham. together with Thames-derived filtered
water.
All the water is chlorinated before it leaves the works.
Contact tanks are in operation at all these works to give opportunity
for the chlorine to exert its full effect before the water is pumped
into supply. Any residual chlorine in the well waters is completely
removed before the water leaves the works.
Bacteriological analyses of all supplies are made at least five
times a week and in the case of the river-derived supply the water
is tested bacteriologically at all stages of purification. All new
and repaired mains are disinfected with chlorine before being
restored to use and samples of water from them are tested to
establish that the quality of the water is up to the standard normally
supplied.
None of the supplies is plumbo-solvent.
The closest watch is kept for any evidence of deterioration
in quality whether physical, chemical, bacteriological or biological
and immediate action is taken if the results of analyses are not up
to standard on the works and in the distribution system.
The following table gives the average results of the chemical
and bacteriological analyses of the various supplies to ihe area
for 1956