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Environmental Health
85
Twelve samples of mains water were submitted to the laboratory for bacteriological examination
and all were found to be satisfactory. A further 21 samples were taken from indirect supplies, i.e.
mains water which had been supplied via intermediate storage tanks, these were also found to be
satisfactory.
Private Water Supplies
There are now only two houses within the Borough without mains water supplies.
In addition, a number of industrial premises draw water from deep wells for manufacturing
purposes.
Twenty-four samples from well supplies were submitted for examination, five of which were
classed as unsatisfactory, of which one was from a domestic well supply and four from two wells
supplying industrial premises.
The failure in the domestic supply was an isolated one as was the situation in one of the industrial
supplies. Although no action has been taken to provide alternative sources, regular samples are being
taken to monitor the existing supplies. As far as the other industrial supply is concerned a mains
service has now been provided.
Water Dispensers
Water dispensers are now becoming fairly common installations for the supply of chilled water
in offices, shops, factories and public places. Some are connected directly to a mains service and others
are filled by hand.
Samples taken from these installations have been poor, 9 out of 13 proving unsatisfactory on
bacteriological examination. Further investigations will be made and a report on the findings submitted
at a later date.
Ice Cubes
One sample of ice cubes submitted for examination was found to be satisfactory.
Swimming Baths
In addition to Ruislip Lido, part of which is used for bathing purposes, there are 19 swimming
pools in the Borough situated at schools, hotels and clubs, etc. Two indoor public pools and one
indoor club pool are in use throughout the year and the remainder during the summer months only.
It has been suggested that no sample from a pool should contain any coliform organisms in
100 ml of water and that in 75% of samples examined from that bath a plate count at 37°C from 1 ml.
of water should not exceed 10 colonies, and in the remainder should not exceed 100 colonies. It is
further suggested that where reliable test facilities are provided and the free residual chlorine figure
at all times exceeds 0.1 parts per million it may be reasonable to omit a coliform test. Consequently
it was decided to reduce the number of samples submitted for bacteriological examination, but the
department carried out regular determinations on the free residual chlorine at all pools.

The unsatisfactory results were obtained from a hotel pool and club pool and were the result
of inadequate chlorination.