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54
(C) Water Supplies - Miscellaneous
Three samples of sub-soil water were taken,
(d) Swimming Bath Water.

By courtesy of the Chief Superintendent & Engineer of Baths and Washhouses the following
information is included in this year's Report:-
There are ten swimming baths under the control of the Council one of which is out of
commission at present.
The Metropolitan Water Board supply the water for these baths.
The method of treatment for purification is by chemical dosage, alumina ferric is the
coagulant used to fulfil the function of forming a film on sand. Soda ash is the alkaline
salt to counteract acidity A pH value of between 7.4 and 7.6 has proved most satisfactory
to the swimmers using these baths.
Aeration is mainatined by means of an air compressor.
Sterilization: Chlorine gas is used, a residual of 0.5 to 0.75 p.p.m. being strictly
adhered to. In the summer months when heavy loads are to be expected it is kept at 0.75 p.p.m.
The frequency of changing the baths water is governed by the flow through the filters
which, in the case of these establishments is approximately once every four hours. In the
summer months when the baths are open for 12 to 14 hours daily a complete turnover of three
times per day is necessary.
During the last twelve months the bacteriological examination reports have been exceptionally
good for all establishments, showing the water to be practically sterile.
Samples of the water at Highbury Field Open Air Swimming Pool, which is controlled by the
London County Council, were also taken during the summer season for bacteriological examination
The County Council were kept informed of the results all of which were satisfactory and
are included in the figure given at the head of this section.