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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. All of
the samples of river water were clear and transparent when drawn
from the mains, a fact creditable to the Companies as evidence of
the care taken in filtration.
THE WATER EXAMINER'S REPORT.
Supervision of the water supply is vested in the Water
Examiner appointed under the provisions of the Water Act, 1871.
This office is held by Major-General A. de C. Scott, R.E., to
whose Annual Reports I am indebted for many of the following
particulars. General Scott's Report for 1890 is not yet published,
but I am indebted to that gentleman's courtesy for a sight of some
of the Tables which will be included in it, and of which I am
permitted to make use. The duties of the Water Examiner are
multifarious. He makes monthly inspections of the several Metropolitan
water works, filter beds, reservoirs, &c.; examines the
quality of the water, both at the intakes and after filtration at the
works; and reports, monthly, the results of such inspections and
examinations to the Local Government Board. Upon him rests
the responsibility of seeing that the requirements of Section 4 of
the Metropolis Water Act of 1852 are complied with—viz., that
"every Company shall effectually filter all water supplied by them
within the Metropolis before the same shall pass into the pipes for
distribution." The effectual filtration of river water depends
upon:—
"1. A suflicient area of properly constructed filter beds, constantly
cleaned, and fresh sanded from time to time as the original thickness is
reduced;
"2. The rate of filtration being controlled and limited to a certain
speed ;
"3. The water delivered into the filter beds having been previously
stored in subsiding reservoirs, and the capacity of these reservoirs being
such as to avoid the necessity for the intake of turbid and muddy water
during the time of extraordinary and heavy floods, which tend to foul
and choke the filters."