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The number of bacteria growing on agar per c.c. in—
1 day at 37°C. : 0.
2 days at 37°C. : 0.
3 days at 20°C. : 9.
B.coli absent in 100 c.c.
The analyst's summary read:—
" This sample is clear and bright in appearance, neutral in reaction
and free from iron and other metals. It is hard in character though not
to an excessive degree, contains no excess of salinity or mineral constituents
in solution, and is of very satisfactory organic or bacterial purity.
These results are consistent with a pure and wholesome water suitable
for drinking and domestic purposes."
In addition, copies are received regularly from the analyst of the
Colne Valley Water Company of the results of analyses carried out on
samples of water collected from houses throughout the district. These
have been uniformly good.
Some diseases may be water-borne. In order that the water company
shall be aware of the occurrence of these, the practice has been instituted
of sending them particulars of households at which such a patient is
resident even though there is nothing to suggest that in that particular
case the infection was attributed to water.
SEWERAGE AND SEWAGE DISPOSAL.
In the early part of 1936, the last of the five sewage disposal works,
which had, up to that, treated the sewage of the district was abandoned,
since when practically all sewage from this area has been treated under
the West Middlesex Drainage Scheme at the disposal works at Mogden,
where it is treated by the activated sludge process. There are still some
few houses on the northern fringe of the area from which the sewage is
treated mostly in small plants in the grounds of the houses, the effluent
finding its way to a water course.
Two trunk sewers and nine main intercepting outfall sewers are of
such capacity that it is calculated on a dry weather flow of 40 gallons per
person per day they can serve an ultimate population of 330,000. The
length of the County Council trunk and outfall sewers in the district is
10 miles and of the district council's foul sewers, 215 miles. There is
a pumping station in South Vale, Sudbury, for lifting sewage from the
South Vale area some 80 feet into the high level sewer in South Hill
Avenue.
The surface water passes by separate sewers to water courses, the
215 miles of surface water sewers and culverts being vested in the district
council. The open watercourses are under the jurisdiction of the County
Council, though those lengths which have been culverted and so have
become sewers, are the responsibility of the district council.
There are five main watercourses in the district. The river Pinn,
which is under the control of the Thames Conservancy, rises in the Royston
Park Estate, runs in a southerly direction to High Street, Pinner, during