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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." He considered that 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.
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 190.4; of the Kent Company's water 28°'6 ; and
of the Colne Valley Company's water only 50-2. The difference in
hardness which the waters exhibit is of no material importance when
they are used for drinking, but when used for laundry purposes the
advantages of soft water, like that furnished by the Colne Valley Company,
are very great. In the washing of linen soft water is indispensable,
and if the water is not delivered soft it must be rendered soft, either by
means of carbonate of soda or by means of soap which is still more
costly. When water is softened in detail by the laundress, the operation
costs, for an equal volume of water, about eighty times as much 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, naturally hard, being
drawn from the chalk, is artificially softened before distribution,
All waters, save artificially prepared distilled water, contain more or less
"solid matter." A large proportion of this solid matter consists of
mineral salts which in no way impair the quality of the water for
drinking, but they render the water hard. A small proportion of the
solid matter, on the other hand, is always organic. Small quantities of
organic matter of vegetable origin are not objectionable in drinking
water, but the organic matter of animal origin in rivers, which receive
sewage, may at any time become dangerous to health.
The deep-well waters delivered by the Kent Company and by the Tottenham
Board of Health, contained the largest proportions of solid matter ; but
the deep-well water derived from the same source and supplied by the
Colne Valley Company, contained little more than one-fourth of the
quantity found in the river waters, and less than one-fifth of that in
the Kent Company's water; this comparative freedom from saline
matters being attained by adding a small quantity of slaked lime to
the water (Clark's process) before it leaves the Company's works. All
the water supplied to the Metropolis would be improved by being
submitted to the same process or one of its modifications.
Owing to the careful filtration to which the river water is now subjected
together with the improved means of storage at the command of the