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CHAPTER VI.
SYSTEMATIC ANALYSIS OF THE WATER OF THE KING INSTITUTE WELL.
The subject of the influence of meteorological conditions on the bacteriological
flora of a shallow well, is one of surpassing interest in India, where the great proportion
of the rural population depends on such sources for their drinking supply. Conse-
quently a :weekly analysis of the King Institute well since July 1908, studied in
relation with the rainfall, should give much valuable information.
The King Institute well falls under the category of what are termed shallow
wells, that is to say, there is no impermeable layer of soil or rock between the water
bearing strata and the ground level, so that surface water can find its way into the
well, by percolating through the soil. The geological formation in the neighbourhood
is disintegrated laterite gravel; it is extremely porous. The well is thoroughly satis-
factorily built of masonry to a depth of 33 feet, so that any surface water, that may
its way into the well, has to pass through 30 feet or more of soil. The floor of the
well is actually in a layer of river sand. The well is provided with a pump and oil
engine capable of lifting 7,000 gallons per hour; every day 25,000 gallons are pumped
out and discharged into the cistern in the King Institute compound, some 1,000 yards
away. Careful account is kept of the amount of water drawn and it is found. to vary
very little from day to day. The surroundings of the well may be described as fairly
good and. clean. It is situated in the midst of a thin scrub jungle, where cultivation
is impossible, and. there is little vegetation that would attract any animals except goats.
The immediate surroundings are not fenced. in, so that there is slight possibility,
though no great probability, that animals may stray into the neighbourhood.. The
river Adyar is situated about 200 yards away from the well. This river is considerably
polluted. in its whole course, but the grossest pollution takes place below the King
Institute where some hundreds of dhobies wash clothes. Engine attendants are daily
present in the engine house, but arrangements are made to see that they pollute the
ground as little as possible.
The analyses were begun early in July 1908. Previous to this there had been little
or no rainfall for six months. The rainfall for April, May and June was only .3 of
an inch. Consequently the early analyses were begun under what may be termed.
typical hot weather conditions. At this time of the year the level of the sub-soil water
was 16 feet below the surface of the ground, the depth of the water in the well being
also 16 feet.
Sample No. 1.—Shows that fecal bacilli were present in 5 cc. of the well water.
There had been practically no rain during the week with the exception of very light
shower which scarcely wetted. the 'soil. The preponderating bacilli present in the
were B. cloacm. It is not maintained that when an analysis shows only one organism
present, no others are to be found in water, but when this occurs, there is no doubt
that the organism isolated preponderates to a very great extent.
Sample No. 2,—During the week ending 9th July 1908 3 of an inch of rain
fell at the King Institute, that is to say there was one fairly heavy shower. As a
result of this, very considerable alterations have taken place in the quality of the well
water. It will be observed. that fecal bacilli are now present in 01 of a cc. instead.
of in 5 cc. in the last analysis. Further of the 10 colonies isolated from the water
one is B. coli communis. It seems extraordinary that, such a comparatively small
amount of rain should so greatly increase the amount of pollution present; this
contamination cannot come from the surface, otherwise a great mixture of organisms
would be found. instead. of only cloacae. Evidently therefore a slight fluctuation of
the sub-soil level must wash a large number of the organisms, that are probably
present in the deeper layers of the ground, into the water.
Sample No. 3.—During the week 7 of an inch of rain fell on the 11th instant.
This rainfall represents only one heavy shower, it probably was all over in half an.
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