View report page

5
We cannot hope to get water absolutely free from this impurity, and we have
good evidence that water may contain a small quantity of some kinds of organic
matter without any bad effects. It is the condition rather than the quantity of
this impurity which decides its salubrity. Organic matter, derived from animal
excreta, such as now find their way into the Thames, and other organic matters,
which are undergoing decomposition, render water especially injurious. There
is always a risk of such contamination in shallow wells, in large towns, which
are therefore in my opinion much to be deprecated, and ought not to be allowed
for drinking purposes. By chemistry it is very difficult to do much more than
determine the amount of organic matter, and even this determination requires
some of its most delicate processes.
In support of the statement that the quantity of organic matter in water is not
alone an exact measure of its noxious properties may be mentioned the fact that
the Government Commission of 1851, found in the Battersea water, supplied by
the Southwark and Vauxhall Company, the use of which so much increased the
fatality of cholera, less organic matter than was found in the waters from
Thames Ditton, which was so much less injurious. If, however, a water contain
above a grain of organic matter, especially if it also contain nitrates or ammonia,
these constituents though not in themselves necessarily injurious, should yet
excite suspicion, and lead to a careful investigation of all possible sources of
contamination to which the water is liable. They may be taken as evidence
that the water has traversed a soil more or less impregnated with organic refuse,
and there is always a risk that the organic matters may either, in some stage of
their decomposition, or from a difference in their origin, or from some predisposing
epidemic influence, acquire noxious properties which at present they
do not possess. The most important lesson taught by the experience, gained on
the subject of drinking waters in towns, is to remove them from every possible
risk of contamination by animal excreta, such as arises from sewerage running
into rivers, or from cesspools and drains communicating with shallow wells.
The presence of microscopic animals and vegetables in water is an indication
of organic impurity in a state of change. Their germs are at all times floating
in the atmosphere, and their development is much promoted by light, air, and
warmth. Their formation is checked by the use of water receptacles, which are
securely protected from light and air by well fitting lids.
At the end of this report are given the results of analysis of waters supplied
by the three companies. It will be seen that the amount of organic matter which
they contained in 1856 was much less than that given in 1851; and they also
contain considerably less organic life. The amount of inorganic matter has undergone
but little change; their hardness is about the same.
The water, as available to the majority of the inhabitants of the parish, is,
however, very far more impure than the water as sent out by the Companies.
Its extra impurities are due to the mode of supply and the defects of storage.
The ordinary receptacle for water in the poorer houses is a wooden butt, frequently
uncovered; it is often much decayed, and lined with filth and organic
growths. Its situation is usually near a foul privy or decaying dust heap, or in
a damp cellar; the water thus becomes saturated with dust, dirt, and noxious
gases. Water has a very remarkable power of absorbing and holding in solution
gases which come near it, such as ammonia, sulphuretted hydrogen, which are
the results of decomposition, and frequently carry with them animal and vegetable
substances in a high state of putresence. In many cases the water-butt is
not furnished with a tap, so that the water is taken out of it by any stray
vessel, on which hands are laid. Another effect of such storage as this is
the high temperature to which in summer the water reaches, which very much
deprives it of all its thirst-quenching qualities, and very much increases its other
defects. In some places there are underground tanks to supply a pump for the
use of a number of houses. These tanks are objectionable from the risk of contamination,
and from the difficulty with which they are cleansed. The additional
labour entailed in obtaining water by this mode of supply is sufficient very much
to diminish the amount of it used by many who are not very fond of its use.
Within a very recent period, two of these cisterns have come under my notice in