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and solely this—they are a quantitative and exceedingly delicate test
of the efficiency of the filtration to which the water has been
subjected, and they prove, in the case of the river waters delivered in
London, how very efficient, as a rule, is the sand filtration, as carried
out by the Water Companies, for the removal of microbes and their
germs"— even to the extent, in some instances, of 99 per cent. of the
germs contained in the original water at the intakes. "In this
enormous reduction there is obviously a considerable, though by no
means absolute, guarantee that pathogenic organisms, if present,
would disappear with the crowd. Nevertheless, it is only by the
rejection, for dietetic purposes, of water polluted by excrementitious
matter that immunity from water-borne zymotic poisons can be
secured."
From the Sanitary point of view Dr. Frankland has
always maintained that the deep well waters are very
superior, the exhaustive filtration they undergo, in passing
through a great depth of porous strata, being far in excess
of what can be effected by the sand filtration, highly valuable
as it is, to which the river waters are subjected.
THE WATER EXAMINER'S REPORTS.
Supervision of the water supply is vested in a Wattr
Examiner, appointed under the provisions of the Water Act,
1871, whose report for 1891 has not yet been published. The
duties of the Water Examiner are multifarious. He makes
monthly inspections of the several Metropolitan waterworks,
filter-beds, reservoirs, &c.; examines the quality of the
water, both at the intakes, and after filtration at the works,
and reports the results of such inspections and examinations
to the Local Government Board. From these monthly
reports some of the subjoined information respecting the
water supply has been obtained. Upon the Water Examiner,
moreover, rests the responsibility of seeing that the requirements
of Section 4 of the Metropolis Water Act 1852 are
complied with—viz., that "every Company shall effectually