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What Is A Well?


Basically, a well is a hole drilled into the ground to access water contained in an aquifer. A pipe and a pump are used to pull water out of the ground, and a screen filters out unwanted particles that could clog the pipe. Wells come in different shapes and sizes, depending on the type of material the well is drilled into and how much water is being pumped out.

More than 42 million people in the United States use individual or private wells to supply water for their families.

Three Basic Types Of Wells

  • Bored or shallow wells are usually bored into an unconfined water source, generally found at depths of 100 feet or less.

  • Consolidated or rock wells are drilled into a formation consisting entirely of a natural rock formation that contains no soil and does not collapse. Their average depth is about 250 feet.

  • Unconsolidated or sand wells are drilled into a formation consisting of soil, sand, gravel or clay material that collapses upon itself.

Well Construction

All private well construction is based on establishing the right location for the well, sizing the system correctly and choosing the proper construction techniques. Only professional water well contractors should install wells. They are familiar with the hydrology in an area and all local codes and regulations. Proper well construction is key to operating and maintaining a well.

A well is composed of many components. The most important materials used include:

  • Casingis used to maintain an open access in the earth while not allowing any entrance or leakage into the well from the surrounding formations. The most popular materials used for casing are black steel, galvanized steel, PVC pipe and concrete pipe.

  • Grout is a sealant that is used to fill in the spaces around the outside of the well. It protects the well against the intrusion of contaminants. A grout mixture can be made of cement, bentonite, or concrete (each used separately).

  • Screen keeps sand and gravel out of the well while allowing groundwater and water from formations to enter into the well. Screen is available in many materials, the most popular being stainless steel and slotted PVC pipe. Screen is used when wells are drilled into unconsolidated materials.

  • Gravel packis placed around the outside of the screen to prevent sand from entering the well or clogging the screen and to stabilize the well assembly.

Well Contamination


A well can easily be contaminated if it is not properly constructed or if toxic materials are released into the well. Toxic material spilled or dumped near a well can leach into the aquifer and contaminate the groundwater drawn from that well. Contaminated wells used for drinking water are especially dangerous. Wells can be tested to see what chemicals, pathogens and other contaminants may be in the well and if they are present in dangerous quantities.

Things you can do to protect your groundwater and water well:

About Your Well

For information on your well, contact the well contractor who installed it, or locate a water well contractor in your area by looking online or in your local telephone directory. For more information on drinking water and private wells:

Special thanks to the Water Systems Council for contributing information contained in this article.

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