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Valley Company, which was softened before distribution by the process above
mentioned.
All waters, save artificially prepared distilled water, contain more or less "solid
matter." The solid matter in river water is composed of a variety of substances,
by far the largest proportion being entirely harmless when the water is used for
dietetic purposes, but a small proportion consists of organic substances, which are
always objectionable, and at times are dangerous to health. The average proportion
of total solid matter was rather less than in 1879. The deep-well waters
delivered by the Kent Company and by the Tottenham Board of Health, contained
the largest proportions of these matters; but the deep-well water supplied by the
Colne Valley Company contained less than one-half the quantity found in the
river waters, and less than one-third of that found in the Kent and Tottenham
waters: this comparative freedom from saline matters being attained, as already
explained, by adding a small quantity of slaked lime to the water before it leaves
the Company's works.
The organic impurities derive their importance from being, to a great extent, of
animal origin. They are found in the river waters, which last year were often
much polluted, so that, even after efficient filtration, Dr. Frankland deemed them
in some measure fit to drink only during the months of May, June and July.
Never since these analyses have been made had the Thames water been so much
polluted by organic matter as in 1880. The nearest approach to this degree of
pollution was reached in the year 1872, but at this time the several companies
were provided with far less efficient apparatus for filtration than at present, so that
the actual pollution of the unfiltered Thames water during the last year must
have been even still more strikingly in excess of that of previous years. Owing
to the flooded condition of the river, even in summer, much filthy matter from
sewers, cesspools, and cultivated fields was swept into it during those periods of
the year when they are usually kept back through the absence of heavy rain.
No practicable amount of storage capacity could have prevented the supply of such
water during the last three years. The water is becoming year by year less
suitable for domestic use. These "noxious organic matters" are "in suspension,"
but in such a finely divided state as to render their removal by artificial filtration
through sand impossible. There is thus no protection against the distribution of
them in polluted river water. Deep-well water, on the other hand, has undergone
such a prolonged and exhaustive filtration through great thicknesses of porous
strata, as to render it extremely unlikely, if not impossible, that any portion of
the organic matter still remaining in it should be of this objectionable character.
Hence the deep-well waters are "uniformly pure and wholesome." Of the river
water abstracted from the Thames, the best average supplies were furnished by
the Chelsea and West Middlesex Companies. Not many years ago the supply by
the Chelsea Company was one of the worst, owing to the unsatisfactory position
of their intake—at Seething Wells—and to deficiency of storage reservoirs.
Stimulated by the complaints of their customers the Company removed their
intake to West Molesey, undertaking extensive works at a large outlay, and now
they are enabled to supply water even superior in quality to that of the West
Middlesex Company, which for several years was at the head of the Companies
drawing their supplies from the Thames, but which in 1880 showed the highest
maximum as well as the lowest minimum of pollution.