The Sun.
London, England, 1851-06-26 00:00:00

OF THE PROPERTIES TO BE PREFERRED IN THE WATER

SELECTED FOR THE SUPPLY OF THE METROPOLIS.

The properties which we would esteem of the most
value in water to be supplied to the metropolis are:-
1. Freedom from putrescible organic matter.
. .

2. Freedom from constant, or even occasional discolo-
ration by clay and vegetable matter, with perfect bright-
ness and clearness.
3. Softness.
4. Coolness.

The nearer the sources of rivers are approached, the
mcro fully are they likely to possess the two first re-
quirements, freedom from organic impregnations and
from colour. The New River water may be instanced
as offering the most favourable exhibition of the good
qualities possessed by any portion of the present me-
tropolitan supply. Taken from the Lea, above Ware,
this water has a superiority, which is generully ad-
mitted, over the supplies from the Thames, which would
no doubt be further increased by the removal of the
Hertford drainage, by recourse for additional water to
the higher tributaries of the Lea, as proposed by the
River Lea Trustees, and by shortening the chanel of the
New River by about 12 miles, which is also contem-
plated. But it is only by proceeding to the actual
sources of rivers that the water of the latter can be pro-
tected completely from field and house drainage. Hence
the general disposition to abandon rivers as sources of
town supply, and to allow them to remain as they must
always be, the natural and indispensable channels of
drainage, and the occasional means of fertilizing irri-
gation.

The contemplated improvement of the New River ap-
pear to embody a portion of the comprehensive scheme
of Captain Vetch, who, after a careful survey under-
taken by direction of the late Metropolitan Board of
Sewers, recommended the appropriation of the unob-
jectionable chalk streams on either side of the Thames
us the future sources of supply ; abandoning the river
itself for its purer tributaries, and giving a preference
to those streams which enter the Thames below
London, so as to retain the volume, and scouring
power, and with these the salubrity of the upper
part of the river unimpaired. To this last object Cap-
tain Vetch attached great importance with reference to
the prospective increase of the metropolis, which he re-
minds us has doubled its population within forty
years. The eminent engineer, Lir. Tedford, to
whom the question of the metrppojiten stip& was
referred by Government after the ivatere Tnqill7s
and report in 1828, had previously Ipecommended,
after a prolonged investigation, td bring the water from
the river Verulam, near Watford, for ithe supply of
the districts ou the north side of the TZtahaips, and
from the river Wandle for the supply of th districts
on the south side. Iu IS4O a further step was taken

in the same direction, " The Londqn and Westraiu-
attr Water .Works Company" being at that time estak
fished for supplying the metropolis witli atei frtil the
springs in the chalk, near Watford. This company pro-
ceeded upon a report by Mr. Robert Stephenson, which
appears to be founded on sound scientific principles and
great local knowledge. Mr. Stephenson concludes that
the necessary supply for Loudon, could be obtained and
conveyed from that source, and speaks in the highest
terms of its quality. He expresses his surprise, that
with the exception of the abortive project to obtain water
by perforating the London clay, all preceding proposals,
"including Mr. Telford's, should have contemplated using
the water of streams which aro all subject to be affected
by the surface drainage of a more or less extensive tract
of country, and consequently only a very few degrees
better than that already in use."
Our great engineers have thus returned step by step
to the original idea of Sir Hugh Middleton, who had
recourse to the pure fountain heads of Hertfordshire for
the supply first brought by him to London by the New
River, acting, no doubt, upon the traditions of an-
tiquity and the example of the Roman hydraulic works,
which are still unrivalled. Of the two divisions of Hert-
fordshire which are drained respectively by the Colne
and the Lea, the former, or north-western district, con-
taining 'Watford, appears to exceed, in available water
sources, the latter, or north-eastern district, the field
which is already occupied by the New River Company.
The inhabitants of London appear to have within
their reach, in these chalk strata, a supply of water,
which is asserted, on good authority, to be inexhaus-
tible, and which may be considered as everywhere of
an uniform composition and quality. The rain falling
upon the downs and elevated ridges is rapidly absorbed
by the soil, and enters the chalk beds, through the
porous and amply aerated channels of which it circu-
lates, much of it probably for centuries, before subsiding
to the: lower level of the valley springs. Hence a full
decomposition of any alterable organic matter, and the
assumption by the water of a constant end uniform
character.

The chalk spring-water unites the greater number of
the desirable qualities already enumerated. It con-
tains absolutely nothing of organic origin capable
of further alteration or decomposition, and is is therefore
wholly unobjectionable, on the ground of organic con-
stituents. Its clearness and brilliancy also appear
perfect, from the complete absence of suspended matter,
and are highly attractive. Possessing at all seasons
the mean temperature of the year, the same water
has an agreeable coolness and freshness, which might
certainly be preserved in a great degree by proper
means of conveyance and distribution. The only other
quality desired in a town supply was softness. The
enalk spring water is not naturally a soft water. In
this resi:ect it is inferior to the present supply, in one
sense, being one-fourth harder; but it will be remem-
bered that the hardness of both is principally of the
temporary kind, and that, after boiling, the advantage
is with the spring water. It is, however, in the faci-
lity and completeness of the removal of this hard.
'less, that the superiority of the spring over the
river water is most apparent. The softening operation,
by the use of lime, is applicable in all seasons to the
:Tang water, which, indeed, adapts itself with singular
felicity to that process, the carbonate of lime always
precipitating with rapidity, and so completely as not
to create a necessity for filtration. The chalk spring '
waters can thus be commanded with certainty, under
three degrees of hardness, which is probably the extreme
limit attainable anywhere in England for a great
supply, The lower price of lime in the chalk districts,
and the reduction in the labour of mixing, must also

bring the cost of the process considerably within
the estimate formed at the Chelsea Works, end
would not, wo believe, form a greater addition than a
sum equal to two per cent. upon the present price ot water.
This is without allowing anything to be obtained in return
for the precipitated chalk, which would certainly have
some market value.
The chalk spring water after being softened is an ex-
tremely pure water. It appears to be considerably su-
perior even to the soft water from the streams or the
Surrey Sands. The chalk water alone. is uniform in its
excellence at all times, the sourccls of it lying beyond the
influence of weather or season.
Commissioners, this softened
from its chemical quality, chnaltkhewatedrgniiretntitled,
of the preferencemetrpois.
to a
for the future supply
It is no longer possible to di • all others
for over
of removing hardness, or disregard the chtehmeLealanis means
tor to repre
im-
practicable on
ques-
tion of scale; tll
entirely new footing.
resent them
the ques-
Efficient as these water-supply means already.
upon an
are, we con-
fideutly look to
the large '-their further improvement, when
results of practice come under the eye of
the engineer and scientific observer. .tnother mode
of partial softening, without tho consumpt.ion of limo or
any other material, by the united action of air and
granular carbonate of lime upon the carbonated water,
has been already referred to, which may probably soon
have its powers tested, either as an auxiliary to Dr.
Clark's process, or as a substitute for that process, when
a less considerable softening is required.
An incidental advantage of artificial softening for the
London supply
is, that the change in quality eau be gra-
duated to auy point desired. It may be advisable to fur-
nish the water at first with a hardness of five or six de-
grees, which is considerably above the point at which
any ac.ion upon lead need be apprehended, and there •
fore compatible with the cisteru storage of water,
which the actual system of supply requires. The
cir-
cumstance that this residuary hardness after Liming
absence
yields readily to boiling, combined with the
f:om the spring water of all colouring impurity, would
la
insure that water a decided preference for washing
most other applications, even were it no farthersoftened. But it might be reduced, we believe with
perfect Eafety to three degrees of hardness, as soon as
the taste and habits of the consumers were accomwo.