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64
epidemic, there can be little doubt that the disease was for the most
part waterborae. It is not quite clear, however, whether pollution
occurred centrally or peripherally. Both central pollution of the
well itself and peripheral pollution of the watermains were shown
to be possible. Probably both were concerned in the epidemic,
though 1 should personally be inclined to ascribe the larger share to
the central source of contamination.
Shortly after this epidemic steps were taken to line the wells for
a greater depth, and, from that time till now, enteric fever has never
been epidemic in Croydon. Comparison of the "Croydon" and
" Lambeth " water areas of the Borough also shows that the small
amount of enteric fever that has been prevalent during recent years
has been fairly equally distributed over both areas. (See page 18.)
Unfortunately, however, the situation of the wells and certain
analytical results render it very doubtful whether the reputation of
the last thirty years can long be maintained. As already stated,
Well No. 2 has had to be abandoned because it has become contaminated
and the connection between all four wells is so intimate
that there is no guarantee that the remaining wells may not suffer
a similar misfortune, especially as the area from which the wells
derive their supply is becoming more and more thickly populated.
The reality of this risk is emphasised by the fact that bacteriological
examinations already indicate occasional departures from the high
standard of purity which should be maintained by wells in the
chalk. A fissure is also known to exist from Surrey Street to the
Addington Hills, and there must therefore be some increased risk
of pollution on the growth of the town in that direction.
The demand for water always tends to overtake the supply and
thus lead to over-pumping with the obvious risk of unduly extending
the cone of depression, and so sucking sewage into the wells.
It is true that the sewers and drains within a radius of a ¼ mile
of the well have been carefully constructed, and are constantly
inspected, but it is impossible that all should be watertight.
Unfortunately, neither the capacity of the sewers to keep sewage in,
nor the capacity of the well linings to keep sewage out, can be
thoroughly tested while we are dependent on Surrey Street for the
bulk of our water supply.
Should an intermittent supply have to be. substituted for the
present constant service there would also be some risk of the water
mains being infected, as was said to have occurred in 1875.