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The nine failures on public water supply were found to be isolated results, repeat samples
being satisfactory.
PRIVATE SUPPLIES
There now remains only one house in the Borough without a mains water supply, water
being drawn from a shallow well which, while having a high coliform count, was found to be
free from type 1 coliforms. A number of industrial premises draw water from deep wells for manufacturing
purposes. Unsatisfactory results were obtained from a private supply to a food factory,
the water is used as a coolant only but, as a precautionary measure, chlorination was introduced.
A well supplying a small factory with drinking water was found to be unreliable, mains water was
not available and the company installed a bacteriological filter. Subsequent samples have been
found to be satisfactory.
SEWAGE DISPOSAL
I am indebted to the Director of Engineering, Mr. Basil D. Steele, for the following information:
DESCRIPTION OF SYSTEM
The London Borough of Hillingdon is drained on separate sewerage systems. The foul sewage
is treated at the Mogden sewage treatment works of the Greater London Council and the surface
water is discharged into the drainage areas of the Thames Conservancy or the Greater London
Council. The Borough is divided into natural geographical areas served by district foul sewers which
discharge into the Council's main sewers and thence to outfalls on the Greater London Council's
trunk sewers. The responsibility of the Borough for the disposal of foul sewage ceases at the
point where it discharges into the Greater London Council's trunk sewers which convey the
sewage to Mogden. The disposal of the surface water is through the Council's main surface water
sewers which discharge at a number of places into the rivers flowing in the Borough. The rivers
of the Thames Conservancy Board are the Pinn, the Frays and the Colne and those of the Greater
London Council are the Yeading Brook which flows into the River Crane. In addition, through
the co-operation of the British Waterways Board, a number of surface water sewers discharge
into the Grand Union Canal.
Considerable development and redevelopment has taken place in this Borough since the
sewerage systems were designed and this together with the increased use of water both for
domestic and industrial use, has caused some local flooding. There are a number of areas in which
the sewers are over-loaded to an extent that the addition of a comparatively small number of
connections from new properties may result in local flooding. The Council is undertaking a detailed
examination of the sewerage systems of the whole of the Borough to ascertain the adequacy of
the systems, both for present needs and those of the foreseeable future.
PROGRESS OF RESEWERAGE WORKS
I stated in my last report that it was intended, where inadequacies were found in the system,
to carry out such works as are required immediately and allow in the design of those works for
possible future development.
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