Every evening, Wilmington daily commercial., 1920-07-31
Keeping the Water Pure
b. Frederic J. Haskin.

| thrown CONSERVATION into the ranks al
the sanitariurDs Of the nation by issuing
q statement which said that the lives OF
all those 30,OO0000 people who live
in our cities were endangered because
of the difficulties in getting chemicals
| which make the water supply of the
municipalities pure and wholesome.
The era Of greater healthfuness that
has come to the nation in the last two
decades is largely due to the near elimna-
ton of waterborne diseases. Without
| these chemicals water would continue
| Ia carry its microscopic messengers of
| death Therefore the emergency and
| the haste
| All Of this has had the effect Of direct
ing attention to the miracles which this
| generation has performed in the elmina-
| ton Of the dangers that lurk in drinking
| water. OF the millions who drink from
| the hydrants of the cities. very few appre-
| ciate the fact that every cup Of water
| drunk every day in every city has been
| specially treated 10 make IT safe and whole
| some. The story of the method OF this
| treatment If n romance Of science.
A hundred years ago Vtte WIS done
toward purifying the watch furnished for
drinking purposes To these who lived
In the cities Of the world A hundred
of the earth. and in spots where popula.
tions were concentrated IL ran through
the masses and took an unthinkable
toll
LIGHT ~ RAD FOR GERMS.
In those DAYS the one tendency toward
the publication of drinking water came
about almost by accident. When water
Is stored In n reservoir the suspended
particles in IT sink tn the bottom and
carry down n large percentage of the
germs that lnfcst the water. Water
standing in the sunlight tends to purify
itself because in light the conditions for
propagating germ life are not favorable
II was IN 1929. however, that the first
scientific step toward water publication
was taken AZ that time James Simp-
son, Of London took the initiative which
led to iiltering the drinking supply Of the
English metropolis The principle upon
which he worked dominated efforts to-
ward water publication for ~ years, and
Is still an important item m that work
Simpson demonstrated the advisability of
filtcring water through sand This prin-
ciple, much more highly developed. is
still largely in use.
Many of the reservoirs which hold the
water supplies of towns and cities through
out the United States have carefully
arranged s1eve Of sand in their bottoms
Building one Of these sleeves il n good deal
like constructing paved street First
there is laver of broken rocks. then
another Of smaller size and still a smaller
one. until finally there rs thick LAYER of
sand on top
When water is first put into reservoir
with bottom of this sort the sieve IL
not very effective Even in clear water.
however, there Is certain material which
this sand removes The strained out
impurities of the water make n sort of
scum, which is called gchmutzdecke by
the scientists. the term meaning dir,
cover. from the German.
This dirt cover makes the sand sieve
effective When the conditions are just
right such sieve will remove 90 per cent
Of the germs from any water and make
il comparatively safe for drinking pur-
poses Until near the close Of the past
century the development of sanitary
water supplies was based upon this
principle.
Twenty-Five wears ago an American
took hold Of this principle and developed
what is known as the rapid sand filtra
ton, or American method The old
scheme required too much space for the
spreading out Of the sand sieves The
American method substituted n tank for
the reservoir method. and provided for the
cleaning Of the sand sieve. Within the
tanks which one secs on the high ground
back Of any American city Is one Of these
rapid sand sieves Into this tank
chemical has been introduced 10 take the
place of the schmutzdeckc This chemical
is nothing more than alum. In all water
Il A
when alum comes into contact with il a
prccipitate is formed which converts the
sand into an effective germ strainer
CURRENT WORKS korH WAYS
Only a gwen amount Of water. however.
can he run through this strainer until the
sand becomes 50 full of impurities that II
ceases TO function effectively. Here,
however, the American method meets the
emergency BY a clever appliance the
current of water is reversed and is sent
forcefully up through the sand from the
bottom. 1t removes all the impurities
and the alum-like precipitate and fushes
them from the tank Thus the strainer is
made as good as new. and the water is |
started through it again for effective puri- |
fcation
There is now famine in the supply of |
alum for use In the tanks through which |
the water supplies for municipalities are |
strained This alum comes from a clay |
known as bauNite the chief source Of |
supply of which is in the vicinity of Little |
Rock. Arkansas One of the chief alum |
factories in the country is located near |
Philadelphia. This factory requires four |
carloads of clay day OF late, however |
it hsa been receiving but eight carloads |
q month Similar conditions exist else
where Cities are finding il impossible |
to get their alum, and the menace of pesti-
lence is increasing daily.
There is, however, later development |
IN the work OF water publication, also
of American origin, which is coming into
general use, and which is almost miracu-
lous. AT the little town of DuInwoodie, in
New York, the two great aqueducts that /
carry the water for the metropolis from
Croton reservoir come very near together.
This water supply has not been filtered,
and until it reaches Dunwoodie it has not
been treated to make it safe for the mil
lions who are to drink it.
At Dunwoodie "a little house is built
between the two aqueducts This house
is repository of certain tanks of vita
liquid. From these tanks there comes
forth drop by drop the particles of this
most powerful disinfectant. 1t is diluted
by water, and little stream of it goes
zach way into the great aqueducts. These
little streams purify the stupendous
amount of water that New York uses,
and makes it one of the safest cities from
typhoid in all the world.
WHAT THE GERMANS USED.