8
(a) Municipalities.
The waters-upplies to municipalities in the Madras Presidency are derived
from one of three sources (i) Rivers, (ii) Lakes and reservoirs, (iii) Springs and wells,
and in most cases undergo some type of preliminary treatment prior to delivery to
the consumer.
(i) Rivers.—As most of the rivers dry up entirely for certain periods of the
year, infiltration galleries fed by subsoil streams in the river bed are utilised. In
some places where facilities exist, the water required for the year is stored in earthen
reservoirs and then filtered through sand or mechanical filters. In a few instances
wells and springs are used as the sole supply or to supplement other existing
sources.
Infiltration galleries.—Fourteen out of the 30 protected water-supplies in the
Presidency obtain their drinking water from infiltration galleries. One of these
(Bezwada) is supplied by a pair of infiltration wells on the banks of a river. Each
of these 14 supplies was examined at least twice during the year under report and
the results have gone to show that:
—
(1) the best water is obtained from galleries laid in the beds of streams
whose surface flow is non-existent except as the result of sudden storms,
(2) galleries laid in porous soils of soft rock yield water which is relatively
pure,
(3) all other galleries yield a supply of variable quality,
(4) galleries, as a rule, are incapable of rendering a heavily polluted flood
water safe for drinking purposes.
Slow sand filters.—Ten out of the 30 municipalities use sand filters. None of
these installations have, with the exception of Periyakulam, given uniformly good
results at successive examinations. Cocanada gave very good results at the first
two examinations but the third examination showed a considerable deterioration in
the filtered water. The other eight towns gave very variable and uneven results.
Pipe lines were found to have become fouled and the samples as distributed showed
further deterioration. A short note on the results of examination of the individual
municipal supplies is appended to this report.
Mechanical filters.—Three municipalities employ mechanical filters to purify the
raw water. None of these have given consistently good results at the successive
examinations.
(ii) Lakes and reservoirs. —The three principal hill stations of South India
are supplied with water from reservoirs containing upland surface water without any
further treatment. Of these the Kodaikānal supply was not as good as it might
have been from the bacteriological point of view. Coonoor showed an increase in
its organic content.
(iii) Springs and wells.—Adōni, Cuddapah, Dindigul, Gunt ū r and Kumba
-kō nam depend either wholly or in part upon springs and wells for their drinking
water. The deep subartesian bore-hole spring at Kumbak ō nam alone gave
uniformly good results at two consecutive examinations. The other supplies
were very variable. The Dindigul well was bad and was condemned at all the
three examinations. (Vide Appendix I.)
(b) Jails.
The water-supply of almost all the jails in the Presidency is derived from
wells which apparently are within easy reach of pollution. The majority of these
wells have given most unsatisfactory results at successive examinations. (Vide
Appendix II.)
( c) Railway stations.
Eighteen of the more important junction stations, where there is an incessant
influx of passengers, were selected by Government for the purpose of having their
water-supplies periodically examined.
Five of these are served by the respective municipal supplies. In some cases
municipal water is first stored in railway reservoirs. In certain of these cases
deterioration as a result of storage was noticed.