If you live in a town or city, you probably don't give much thought to how the water you use each day gets to your house. Even small villages often provide a network of supply pipes that transport water to each home in the neighborhood. All you need to know is how to open the tap at the sink.
Move a few miles out of town and the picture can change. While the inner workings are still—thankfully—invisible, your water supply is independent from the neighbor's down the road. Each home has its own well from which to draw water. More than that, each home has its own electromechanical system for getting the water from the well to the house. At the heart of each system is a pump, and the most common types are jet pumps and submersible pumps.
In many areas of the country, finding potable water is as easy as getting out a shovel and digging a hole in the ground. Okay, maybe "easy" isn't the right word, but wherever the water table is only several feet below the surface of the ground, part of the battle may already be over. In such a shallow-well situation, lifting the water up to the house is going to be a little easier, if only because the distance you have to move it is modest.
If your area doesn't have a high water table, or if it lacks a stable supply of potable water near the surface, you must dig deeper to achieve the same result. And because a deep well means that the water has to be lifted farther, the strategies for moving it change.
These days, the most common pump for a shallow well is a jet pump. Jet pumps are mounted above the well, either in the home or in a well house, and draw the water up from the well through suction (see Single-Drop Jet-Pump System diagram on next page). Because suction is involved, atmospheric pressure is what's really doing the work. Think of the system as a long straw. As you suck on the straw, you create a vacuum in the straw above the water. Once the vacuum is there, the weight of the air, or atmospheric pressure, pushes the water up the straw. Consequently, the height that you can lift the water with a shallow-well jet pump relates to the weight of the air. While air pressure varies with elevation, it's common to limit the depth of a jet-pump-operated shallow well to about 25 ft. There is also deep well pump.