View report page

183
from manured land, the effluents from sewage works,
and even raw sewage itself. This animal matter may,
at any time, be accompanied by zymotic poisons
dangerous to health, and although the chances of such
substances reaching the water-consumer are greatly
reduced, both by the filtration to which the water is
subjected by the Companies and by the care which is
exercised in excluding the flood-waters from their
reservoirs ; yet, in spite of these protective measures,
there is no absolute guarantee that the noxious
ingredients, which may at any time be present, are
wholly removed. Most of the Water Companies are
endeavouring to substitute, as far as possible, water
from subterranean sources for raw river water, whilst
the Board of Conservators have almost completely
stopped the discharge of untreated town sewage into
the Thames.
Table A gives the proportion of organic impurity
present in the waters taken from the Thames, the Lea,
and the deep-wells respectively, from 1868 to 1891.
From the figures there given it will be seen that, the
Thames water distributed during the year 1891 has
not been equalled in respect of high average organic
impurity since the year 1882.
Of the water chiefly derived from the River Lea,
that supplied by the New River Company contained, in
every case, less organic matter than that of the East
London Company, which was generally, in this respect,