How Water Wells & Deep Well Pumps Work
Many people in rural areas rely on water from wells for all of their daily tasks. In years past, before technology made city provided water possible, all of our ancestors relied on wells for most of their water needs. The modern rural dweller cannot rely on the city to pump his water to him, and instead must pump it from the ground for himself. It's easy to imagine the city pumping water to us from a processing plant, but less easy to imagine where this underground water comes from, why the ground doesn't just sink into the water, and how it is brought to the surface in the first place. Does this Spark an idea?
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Aquifers
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Water from wells comes from aquifers. Aquifers aren't like giant lakes under the ground; if they were, then the ground would simply collapse into the lake. A simple way to illustrate what an aquifer is, is to imagine a bucket half filled with rocks. If you pour water into the bucket until the rocks are just barely covered, and fill the rest of the bucket with dirt, you basically have a homemade aquifer. The dirt is resting on top of the rocks, and the water is resting in the spaces between the rocks. This occurs naturally when rainwater drains through the dirt, or when water from a stream or other water source seeps into the ground. You can see the effect in action if you go to the beach and dig a deep enough hole. Eventually your hole will be deeper than the water level, and the water will move from the ground into the hole. This is the premise behind a well.
Pumps
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For wells that are not deeper than 25 feet, a simple suction pump will work. These pumps are installed above ground and, as their name implies, suck water up from the well. In the pump, fin-like structures called impellers push the water along. When suction pumps move the water, the negative pressure that is created pulls water from the well. This negative pressure is only strong enough to pull water from about 25 feet down. Many wells, however, need to be deeper than 25 feet in order to provide an adequate level of water. In these cases the pump itself must be submerged into the well. Submersible pumps work on the same principle, but instead of relying on the negative pressure to pull the water up, they use the positive pressure to push it up. These pumps present some challenges because they are powered by electricity, and as such must be water tight. Wires must be run from the bottom of the well to the surface in order to power the pump.
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Pressure Tanks
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If the water pump had to pump constantly to maintain pressure, the homeowner's electrical bill would be through the roof. This problem is solved by pumping the water into a tank that stores it at high pressure. The pump only needs to run until the pressure in the tank falls below a preset amount. Water is pumped into the pressure tank from the bottom. As the water level rises, the air in the tank is compressed, which provides the pressure to the system.
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