Question

"impervious rock" are not suitable for the digging of wells. How? what are they?​

Answer 1

Ground water serves the great majority of people who live in rural areas

and have a water-supply system of one type or another. The reason is

1 that, among the various sources of supply, ground water is by far the most I practical and safe in nature. Even in a highly industrialized country such

as the USA, municipal ground-water installations far outnumber surface-

water supplies. It is very probable that, for a long time to come, ground

water will be the most important source of supply for most rural communi-

ties of the world.

The advantages of ground water are :

(I) it is likely to be free of pathogenic bacteria;

(2) generally, it may be used without further treatment;

(3) in many instances it can be found in the close vicinity of rural I

I / comnlunities ;

(4) it is often most practical and economical to obtain and distribute;

(5) the water-bearing stratum from which it is drawn usually provides

a natural storage at the point of intake.

The disadvantages are :

(1) ground water is often high in mineral content;

(2) it usually requires pumping.

In ground-water-supply investigations and design, the engineer is con-

cerned with the following steps :

(1) to find it in the required quantity and quality as near as possible I

I to the centre of consumption, in order to reduce transport costs ;

1 (2) to extract it by means of a system which produces the quantity

I required, safeguards the quality, and, at the same time, involves the least

I capital outlay ;

(3) to transport the water to the consumer in a way which requires the

least amount of operational and maintenance skill and cost.

This section is concerned chiefly with the first step mentioned above.

Obviously, a rural town or village cannot afford the cost involved in

bringing water long distances by gravity or, much less, by pumpmg.