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160
he being, as is well known, adverse to riparian sources of
supply: Colonel Bolton's observations have reference, inter alia,
to the condition of the water in bulk, at the intakes, and to its
physical qualities when delivered to the consumer—in a word,
to whatever relates to the collection, filtration, storage, and
distribution of the water.
London is mainly supplied from the rivers Thames and Lea, but a considerable
and increasing quantity of water is obtained from deep wells sunk in the
chalk, not only by the Companies which obtain their entire supply from that
source, but also by some of the old Companies, which thus supplement their
intake of river water. The average daily volume supplied per head of population
in 1882 was 28.6 gallons.
Dr. Frankland is consistent in his preference of "deep well water," taking
it as the standard of purity in comparative observations on the waters
generally. In a previous report he described it as being "delicious and wholesome,"
and uniformly excellent for dietetic purposes; maintaining that in the
interests of temperance and public health, it should, as soon as possible, be
substituted for that portion of the Metropolitan supply which is drawn from
polluted rivers. This "pure spring water," he said, is "everywhere abundant
in the Thames basin: in dry seasons it constitutes the sole supply of the
Thames and the Lea, and even after the most protracted drought, more than
350,000,000 gallons of it daily flow over the weir at Teddington, whilst a
further very large volume of it joins the Thames lower down." It would be
a valuable boon to London if even a small fraction of this prodigal supply
could be collected, preserved from irremediable pollution, and distributed to
those portions of the Metropolis which are not at present supplied with such
water. The principal objection to it is its hardness, but this is an objection
easily surmounted by " Clark's process."
The "hardness" of water represents the weight of carbonate of lime, or its
equivalent of other soap-destroying substances, found in 100,000 parts of
water. The average hardness of the Thames water delivered in London last
year was 20.7; of the Kent Company's water 28.5; and of the Colne Valley
Company's water only 5.5. All hard water must be softened before it can be
used for washing linen: when it is softened in detail by the laundress, the
operation costs, for an equal volume of water, at least eighty times as much
(in soap and soda) as it costs when conducted on a large scale by a water
company. The only water suitable for washing delivered in London during
the past year was that of the Colne Valley Company, which was softened by
Clark's process before distribution.
All waters, save artificially prepared distilled water, contain more or less
" solid matter." A large part of this solid matter is saline and unobjection
able in drinking water, but the water is by it rendered hard. A small