Evening star., 1897-02-20
Filtering the Water Supply.

10 the Ed1tOr CT The Evening Star:
In view of the great importance Of adopt
ing some means for purifying and cleans
ing the water supplied by our water works,
the report of Consul Mason as to a new
system adopted at Worms may prove of
interest to our citizens
The matter of filtering the water has
been considered and reported upon time
and again. but has always been condemned
because of the heavy expense of the plant,
and of operating 1t.
General Meigs, who built the original
aqueduct had the water analyzed, and at
the Croton water of New York and for
that reason said 1T does not need to be
filtered"
Various official reports since then have
stated that the water was chemically
pure. In 1886 the Commissioners in their
report say that IF public filtration be re-
sorted to to correct this difficulty Cts tur-
bidity) the cost would be large as to
prevent the immediate consideration of es-
tablishing the plant and Senator Harris
In his report on increasing the water sup
ply, made March 8, 1882 reported against
filtration on account of it's great expense"
The subject was also considered by Col.
Samo in 1919, and again by Gen. Casey in
1sSo, who also objected to it on account of
the great expense. He estimated that to
filter 26OO0,0OO gallons, the plant would
cost 13,4OO, and the running of it s2S 40
per annum. AS the supply is now much
greater than that, and when the tunnel is
completed is expected to reach seventy-five
or eighty million gallons it will be seen
that the cost by the same plan of using
sand beds would far exceed Gen. Casey's
estimate.
However pure the water may have been
IN 1852, when the aqueduct was built,
there can be no question that 1t is rendered
less pure now by the growth of population
md
from sewage, ETC., and that the addition Of
land that is cultivated in the area that
drains into the Potomac and its tributaries
has largely increased the turbidity of the
water, so that low nearly all agree that
something should be done to remedy exist
Ing evils. If, therefore, any plan has been
or can be devised by which the cost of
filtration can be so reduced as to render its
adoption feasible with U.S. 1t is a matter of
great Importance.
In the report Of Consul Mason is a de-
scription OF new system which he de-
scribes and illustrates.
Briefly described the apparatus consists
OF battery or series of porous plates COM
posed of sharp sand and pulverized glass,
paked under high temperature and of
any form desired.
Those in use at Worms are nodded into
nolIow plaques or plates, about forty
inches square and eight inches thick, with
2-lnch space " the center. What they
term a battery Of these are set In a ce-
mented vault into which the water is fed
under pressure of three or four feet head
Ihe water passes through the porous sides
to the space inside, from which it is con-
quoted by pipe, and is thereby filtered on
substantially the same plan as in the Pas
teur nlters in common use in families and
elsewhere
By means of pipes the filtered water can
be fed to the space inside, the pressure on
the outside being removed, when the pas
sage OF the water through the walls from
the inside outward soon removes the dirt
that has accumulated on their exterior
and thus the filter is cleansed without re,
moving or disturbing any of the parts. it
oniy peing necessary to open and close GER
tain cocks.
1t appears from the consurs report that
In 1888 the city of Worms began the fltra-
lon OF Its water supply taken from the
River Rhine, by the sand-bed process, SINH
lar to that used at Berlin. With 1900
square feet of sand-bed filters, they filtered
fSZ5lO gallons per day; but that not being
sumcient they concluded to increase the
system above described. Consul Mason
says:
One of the ten vaults used for the sand
Deos was cleaned out, and 500 of the Fis-
cher plates placed therein. The whole cost
OF the change was 5000. and the new
niters, occupying about one-ninth as much
space as the sand filters. doubled the FL
tering capacity of the entire Installation.
In other words, 500 Fischer plates COSTING
set up and ready for operation, 50, GOO. and
occupying only 130 square meters Of space
uttered as much water as the sand filters
which occupy ITO square meters, and cost
10000" WV
And he adds, that from a long series of
analyses and careful observations made by
the sanitary authorities of Worms, it ap-
pears that the efficiency of the two sys-
tens, worked side by side, is practically
Identical.
If these statements be correct, as we
have every reason to believe they are 1t
would seem that the cost of fltering our
water supply can be so reduced as to make
1t possible for US to have 1t done.
The idea of q commission to examine and
report on the condition and sources of pol
luton Of our water supply is an excellent
one, and II now in addition to that some
means can be provided for an examination
of and report on this new filter system, and
the result shall prove as favorable as rep
resented. we would be in a condition to do
something in the way of filtration by the
time the tunnel can be completed.
w. c. DODGE.
AdaftltEaa