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however, that for the next few years demands on the lowland plains could be met from streams in the surrounding hills, and that with the aid of pipe-lines of small diameter branching off from the main line, most of the smaller distant villages could be supplied. Moreover, such a system would simplify the task of purifying the water.
these conditions
The sinking of
Yet should it happen that owing to distance from the main line, or shortage of suface supplies, the outlying villages could not be economically supplied in this way, then there is a considerable reserve of ground witor that could be drawn upon by means of dug wells lined with concrete and otherwise protected against pollution, and by bore-holes. Dug wells are already extensively used, but they are generally polluted and in some cases yield little or no water towards the end of the dry season;
could casily be remedied by proper construction. bore-holes to a depth of 200 to 300 feet would require an experienced driller and a light, portable, power-driven percussion drill capable of drilling to a depth of 600 feet. The drilling and well-sinking depths would need to be reduced with approach to the sea shore, since otherwise brackish water would be drawn in. Where surface supplies are not available, it may be necessary to bore for water, or to sink wolls with the aid of power pumping-plant, to supply the needs of factories, etc.
In general, ground water supplies from boro-holes are adequate only for small-scale intensive cultivation, as for an acre or two of market garden, and not for irrigation on any considerable
scale.
Water-boring operations should not be undertaken without geological advice, since the occurrence of water in rocks is essentially a geological problem. When bore-hole supplies are likely to be needed geological advice should be sought and trial bores put down. The required advice could normally be obtained by the brief secondment of a water-supply Geologist from a
Colonial Geological Survey.