FIG. 7.
Tube Wells.
Tube wells answer admirably in many localities; it is, however, always essential to have a bore hole made first to determine the stratum which has to be tapped, as the point of the tube may be easily driven through this. An improved form of pump is shown in Fig. [7]; this obviates the danger of impure water being put in the mouth of the pitcher spout pump in order to make it draw.
The great advantage of tube wells is that they enable a stratum, underlying that of impermeable stiff clay which exists in many cases, to be tapped, thus avoiding the danger of contamination by subsoil water. The supply from a tube well is, however, limited in quantity.
Where wells are founded on a clay stratum their efficiency can generally be largely increased at a trifling cost, by driving a pipe lined boring down until water-borne sand is met. Great care must, however, be taken that, when the boring is going on, this stratum be not passed through, and constant tests of the discharge obtained at the various depths are therefore necessary.
Water drawing utensils.
In all cases it is advisable either to provide a pump on a public well, or iron buckets with light chains and wooden pullies, so that private water drawing vessels be not lowered into the water. The pump should be fixed on the platform surrounding the well, and not on the top. A light corrugated iron roof over the mouth of a well is also useful in preventing leaves, and other impurities falling in, and also in affording shelter to the water-drawers.
PLAN OF DOME FOR WELL
FIG. 8.
An effective and economical well cover designed for Ranchi is shown in Fig. [8], page [11]. This, for a 8′ diameter well, costs about Rs. 90.