GUARDING A CITY'S WATER SUPPLY

HOW THE CITY CHEMIST WATCHES FOR THE APPEARANCE OF DEADLY BACILLI; WATER

MADE PURE BY CHEMICALS



BY HENRY J. RICHMOND



"COLON." The city chemist spoke the one significant word as he set down

the test tube into which he had been gazing intently. The next morning

the front page of all the city papers displayed the warning, "Citizens

should boil the drinking water."



Eve y morning, as the first task of the day, the city chemist uncorks a

curious little crooked tube containing a few spoonsful of very ordinary

bouillon, akin to that which you might grab at the quick lunch, but

which has been treated by the admixture of a chemical. This tube begins

in a bulb which holds the fluid and terminates in an upturned crook

sealed at the end. Into this interesting little piece of apparatus, the

chemist pours a small quantity of the city drinking water, and he then

puts the whole into an incubator where it is kept at a temperature

favorable to the reactions which are expected if the water is

contaminated.



After a sufficient time the tube is inspected. To the untrained eye

nothing appears. The bouillon still remains in the little bulb

apparently unchanged. Its color and clearness have not been affected.

But the chemist notices that it does not stand so high in the closed end

of the tube as it did when placed in the incubator. The observation

seems trivial, but to the man of science it is significant.



What has happened? The water contained some minute organisms which when

acted upon by the chemical in the tube have set up a fermentation.

Gradually, one by one in the little bulb, bubbles of gas have formed and

risen to the surface of the liquid in the closed upper end of the tube.

As this gas was liberated, it took the place of the liquid in the tube,

and the liquid was forced downward until there was quite a large space,

apparently vacant but really filled with gas.



It was this phenomenon that had attracted the attention of the chemist.

What did it mean? It was the evidence that the water which was being

furnished to the city for half a million people to drink contained some

living organism.



Now that, in itself, was enough to make an official of the health

department begin to take an interest. It was not, however, in itself a

danger signal.



Not all bacterial life is a menace to health, the chemist will tell you.

Indeed, humanity has come to live on very peaceable terms with several

thousand varieties of bacteria and to be really at enmity with but a

score or more. Without the beneficent work of a certain class of

bacteria the world would not be habitable. This comes about through a

very interesting, though rather repulsive condition--the necessity of

getting rid of the dead to make room for the living.



What would be the result if no provision had been made for the

disintegration of the bodies of all the men and animals that have

inhabited the earth since the beginning? Such a situation is

inconceivable. But very wisely providence has provided that myriads and

myriads of tiny creatures are ever at work breaking up worn-out and dead

animal matter and reducing it to its original elements. These elements

are taken up by plant life, elaborated into living vegetable growth and

made fit again for the nourishment of animal life, thus completing the

marvelous cycle. And so we must not get the notion that all bacteria are

our mortal foes. We could not live without them, and our earth, without

their humble services, would no longer be habitable.



Neither need we fear the presence of bacterial life in our drinking

water. Drinking water always contains bacteria. We, ourselves, even when

in the best of health, are the hosts of millions upon millions of them,

and it is fair to suppose that they serve some useful purpose. At any

rate, it has never been demonstrated that they do us any harm under

normal conditions.



And so, the chemist was not alarmed when he discovered that the

formation of gas in his crooked tube gave indication of bacteria in the

drinking water. He must ascertain what type of bacteria he had

entrapped. To this end, he analyzed the gas, and when he determined that

the fermentation was due to the presence of colon bacilli in the water,

he sent out his warning. Not that the colon bacilli are a menace to

health. The body of every human being in the world is infested with

millions of them. But the presence of colon bacilli in drinking water is

an indication of the presence of a really dangerous thing--sewage.



Thus, when the city chemist turned from his test tube with the

exclamation, "Colon!" he did not fear the thing that he saw, but the

thing that he knew might accompany it.



There has been much discussion of late of the possibility that the great

lakes cities may suffer a water famine. The rapid increase of population

along the borders of these great seas, it has been said, might render

the water unfit for use. This fear is based upon the assumption that we

shall always continue the present very foolish practice of dumping our

sewage into the source of our water supply. The time may come when we

shall know better how to protect the public health and at the same time

husband the public resources. But even at that, the city chemist says

that he hardly expects to see the time when the present intake for

water near the head of Belle Isle will not be both safe and adequate.



No doubt he makes this statement because he has confidence that the

purification of water is both simple and safe. There are two principal

methods. The first, and most expensive, is nature's own--the filter. The

application of this method is comparatively simple though it involves

considerable expense. The trick was learned from the hillside spring

which, welling up through strata of sand and gravel, comes out pure and

clear and sparkling. To make spring water out of lake water, therefore,

it is merely necessary to excavate a considerable area to the desired

depth and lead into it the pipes connected with the wells from which

water is to be pumped. Then the pit is filled with successive layers of

crushed stone graduated in fineness to the size of gravel and then

covered with a deep layer of fine sand. This area is then flooded with

the water to be filtered, which slowly percolates and comes out clear

and pure. The best results in purification of contaminated water

supplies have probably been attained in this way; that is, as measured

by the improvement of health and the general reduction of the death rate

from those diseases caused by the use of contaminated water.



But when the alarm was given this spring by the city chemist there was

no time to excavate and build an extensive filtering plant. The dreaded

typhoid was already making its appearance and babies were dying.

Something had to be done at once.



If some afternoon you take a stroll through Gladwin park your attention

may be attracted to a little white building at the lower end of the

settling basin. It is merely a temporary structure yet it is serving a

very important purpose. Approach the open door and your nostrils will be

greeted by a pungent odor that may make you catch your breath. The

workmen, too, you will notice, do not stay long within doors, but take

refuge in a little shelter booth outside. Strewn about here and there

are traces of a white, powdery substance which seems to have been

tracked down from a platform erected on the roof. This is hypochlorite

of lime, the substance used for sterilizing the city drinking water.



This is so powerful a disinfectant that it destroys all bacteria in

water even in an extremely dilute solution. The method of applying it is

interesting. The city water comes in from the river through a great

tunnel about 10 feet in diameter. The little chlorinating plant is

situated on the line of this tunnel so that the solution is readily

introduced into the water before it reaches the pool called a settling

basin.



The hypochlorite reaches the plant in iron cylinders containing 100

pounds. These are carried up to the roof and poured into the first

mixing tank through a hopper fixed for the purpose. There are within the

building four of these mixing tanks. In the first, up near the roof, a

very strong solution is first made. This is drawn off into a second tank

with a greater admixture of water and thence passes into the third and

fourth. From the last it is forced out into the main tunnel by a pipe

and mingles with the great flood that is pouring constantly into the

wells beneath pumping engines. And this is the strength of the chemical:

five pounds of it mingled with one million gallons of water is

sufficient to render the water fit for drinking purposes. Nearly 98 per

cent of the bacteria in the water is destroyed by this weak solution.

The water is tasteless and odorless. Indeed, probably very few of the

citizens of Detroit who are using the city water all the time, know that

the treatment is being applied.



But the chemist continues his tests every morning. Every morning the

little crooked tubes are brought out and filled and carefully watched to

ascertain if the telltale gas develops which is an index of "death in

the cup." Thus is the city's water supply guarded.



No more important work can devolve on the board of health. Before

science had learned to recognize the tiny enemies which infest drinking

water, typhoid and kindred diseases were regarded as a visitation of

divine providence for the sins of a people. We now know that a rise in

the death rate from these diseases is to be laid rather to the sins of

omission on the part of the board of health and the public works

department.



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_(The Outlook)_