Fig. 22.—How a pump works.
Another remedy is to sink the well deeper, hoping to find a more porous stratum or to increase the head of water in the well. In one well, the writer remembers seeing two lengths of twenty-four-inch sewer pipe, that is, four feet, that had been sunk in the sandy bottom of the well by operating a posthole digger inside and standing on the top of the pipe to furnish the necessary weight for sinking.
Still another remedy is to drive pipe down in the bottom of the well, hoping to find artesian water which will rise into the well from some lower stratum. This method has been successfully employed in the village of Homer, New York, where the public supply formerly came from a dug well twenty feet in diameter. The supply becoming deficient, pipe wells were driven in the bottom and an excellent supply of water found fifty feet below the surface, the water rising up in the dug well to within eight feet of the surface of the ground.
If the well is a driven well and the water in the casing falls so low that the ordinary suction pump will no longer draw, two remedies may be applied. A so-called deep-well pump may be used; that is, a pump which fits inside the piping and can be lowered down to the water level. The ability to bring up water then depends on the power to work the pump and on the presence of the water. Figure 22 shows the principle on which this pump works. At some point, it may be three or four hundred feet below the surface of the ground, a valve A opening upward is set in the well so that it is always submerged. Just above this is a second valve fastened to the lower end of the long pump rod which reaches up to the engine or windmill which operates the pump. At each up stroke water is lifted by the closed valve B and sucked through the open valve A. At each down stroke, the water is held by the closed valve A and forced up through the open valve B.
Fig. 23.—Pump installation.
The other method of developing a greater quantity of water from a deep well is to use air pressure to force the water either the entire distance to the tank or to a point where the suction of an ordinary pump can reach it, as indicated in Fig. 23. In this method an air blower is needed, and since this means an engine for operation, it is not generally feasible, but is suited to occasional needs, where an engine is already installed for other purposes and is therefore available.
The operation is very simple. An air pipe leads from a blower and delivers compressed air at the end of the air pipe, which must be below the level of the water in the well. The pressure of the air then causes the water to rise, the distance depending on the pressure at which the air is delivered.