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GENERAL
Public Water Supplies
The Borough is supplied by three water undertakings—the Rickmansworth and Uxbridge Valley
Water Co., the Colne Valley Water Co., and the South West Suburban Water Co.
All except six houses are supplied with mains water although a number of factories draw
supplies from deep wells.
Twenty-nine samples of mains supplies were taken: 15 were classed as satisfactory but the
remaining 14, all from a new council housing estate, were unsatisfactory. The supply to this estate
had been passed as satisfactory by the Water Company concerned when a count of 9 coliforms
per 100 ml and an absence of type 1 coliforms was obtained, the water having passed through a
newly laid 4" main. This result followed a series in which counts of 180+ coliforms per 100 ml had
been obtained.
Samples were taken by the department and from an initial result of 5 coliforms per 100 ml,
contamination was found to be increasing. The Water Company were informed and spared no effort
in cleaning and sterilising the main; current samples are proving satisfactory.
Nine samples were taken from private supplies and all were satisfactory.
Aircraft Drinking Water
There are two methods of supplying drinking water on aircraft by the fixed tank system and
by portable flasks.
Water is uplifted into the fixed tank system via water bowsers through hoses and couplings.
These have to be maintained in a sterile condition. Water in aircraft tanks becomes a mixture from
varying sources and aircrew carry out tests to determine whether the water contains the correct
amount of free chlorine, and the appropriate quantity of sterilizing agent is added if necessary.
On older types of aircraft drinking water is carried in portable flasks. These are cleaned and
sterilized before each filling at aircraft catering units.
Results of samples are notified to the operating Companies concerned. As in previous years
results of examinations of water from the fixed tank system proved to be more satisfactory than
those from flasks. After repeated unsatisfactory samples from flasks chemical sterilization in addition
to steam sterilization was introduced and this procedure continues to produce the desired results.
Following the unsatisfactory results obtained from siphons, these are now filled from the fixed tank
systems.