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Coonoor .—Climatic conditions appear to have been much the same each year,
and if such continuity can be depended on, it would be well to take steps to ensure
that what might be an excellent supply is not spoiled in transmission. As a rule
the water of the storage reservoir is pretty fair but rarely so good as some of the
Ootacamund sources are. Occasionally also it is considerably polluted which
shows that the gathering ground is not so well conserved as it should be. Usually
the water suffers deterioration on its way to the service reservoir and the town,
and in 1908-09, B. Colis Communis, the type species indicating recent fœcal pollu-
tion, was found in samples drawn from a tap in the town and from the service
reservoir. It is most desirable that a constant service be given for as great a
part of the year as possible. No jointed pipe work can be expected to stand
strong positive pressure alternating with considerable negative pressure, such as
must occur in the pipes of a hilly place like Coonoor when an intermittent service
is given.
Dindigul.—The water was distinctly in better condition in 1910 than in either
of the previous years, in which pollution of a most undesirable kind was found in
the deep well water and in that from the infiltration gallery. The water as
distributed in 1910 was fair only, not so good as in 1908, but much better than in
1909. Very consistent results can hardly be expected when water is drawn from
either or both of two sources yielding such different qualities of water.
Madura.—The Vaigai river is not a good source of supply. In each of the
years the degree of pollution was alike and extensive. The nature of the pollution
was not so objectionable in 1910, probably because the high flood had already
carried off the more recent and dangerous pollution. It is very difficult to even
suggest a possible cause for the extraordinary variation in the quality of the water
drawn from the infiltration gallery. Extraordinarily pure in 1908, extraordinarily
impure in 1909 and somewhere between the two in 1910. Not very much comfort
can be extracted from the 1910 results, as the amount of pollution was as great
then as in 1909. The same proportion of the pollution in the raw water was
therefore passing through the gallery, but, as was pointed out above, the highly
objectionable species of germs were not found in the river water. Had these
germs been present in the river water there is little doubt but they would also have
been found in the water of the distributary system.
Nellore.—There is little new that can be said of the Nellore water-supply.
Sometimes the water as distributed is exceedingly good, sometimes very much the
reverse. Judging by the most recent results the river when flooded gives the
better supply. Under such conditions of course the raw water will be more
extensively polluted, but it would appear that the cleansing action of the gallery
is enhanced. The pipes as usual continue to give material aid in purifying the
water.
Tirupati.—It
is gratifying to note that the infiltration gallery can yield a
good supply even if the river water is bad. In previous years even if the river
water was good, passage through the gallery spoiled it. Generally speaking the
pipes do not bring about any improvement in the quality of the water, usually the
reverse is the case.
Kurnool.—Great variability characterises the quality of the water as supplied
to Kurnool. There does not appear to be any sufficient reason for this. With the
settling tanks properly worked water of reasonable constant quality ought to be
delivered into the pipes, and if such were the case, strange variations in the nature
of the pollution, such as were noted at the last analyses would not occur. Under
the conditions usually prevalent at this season it is not easy to understand why the
supply should be intermittent.
Cocanada.—The
condition of the Cocanada water was rather better in 1910,
but still yields evidence of the effect of some unsatisfactory features of the system
noted in previous years. The indifferent water of the canal is converted into
a good one by storage and is subsequently more or less spoiled by filtration, On
only one occasion has filtration improved the water. It would probably be better
under such circumstances to rely on storage only and to convert the beds into
storage tanks.