Wells are extremely important to all societies. In many places wells provide a reliable and ample supply of water for home uses, irrigation, and industries. Where surface water is scarce, such as in deserts, people couldn't survive and thrive without groundwater, and people use wells to get at underground water.
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Groundwater Wells

Credit: Howard Perlman, USGS
There's a good chance that the average Joe who had to dig a well in ancient Egypt probably did the work with his hands, a shovel, and a bucket. He would have kept digging until he reached the water table, where all the spaces between the rock and dirt particles are filled with water, and water filled the bottom of the hole. Some wells are still dug by hand today, but more modern methods are available.
Wells are extremely important to all societies. In many places wells provide a reliable and ample supply of water for home uses, irrigation, and industries. Where surface water is scarce, such as in deserts,people couldn't survive and thrive without groundwater.
Types of wells
Digging a well by hand is becoming outdated today as automated drilling methods replace manual-labor methods. Modern wells are more often drilled by a truck-mounted drill rig. Still, there are many ways to put in a well — here are some of the common methods.
DUG WELLS
Hacking at the ground with a pick and shovel is one way to dig a well. If the ground is soft and the water table is shallow,then dug wells can work. Historically, dug wells were excavated by hand shovel to below the water table until incoming water exceeded the digger's bailing rate. The well was lined with stones, brick, tile, or other material to prevent collapse, and was covered with a cap of wood, stone, or concrete. They cannot be dug much deeper than the water table — just as you cannot dig a hole very deep when you are at the beach... it keeps filling up with water!
Credit: Roland Tollett, USGS
Dug and bored wells have a large diameter and expose a large area to the aquifer. These wells are able to obtain water from less-permeable materials such as very fine sand, silt, or clay. Some disadvantages of this type of well are that they are shallow and lack continuous casing, making them subject to contamination from nearby surface sources, and they go dry during periods of drought if the water table drops below the well bottom.
DRIVEN WELLS
Driven wells are still common today. They are built by driving a small-diameter pipe into soft earth, such as sand or gravel. A screen is usually attached to the bottom of the pipe to filter out sand and other particles. Problems? They can only tap shallow water, and because the source of the water is so close to the surface, contamination from surface pollutants can occur.
DRILLED WELLS
Most modern wells are drilled, which requires a fairly complicated and expensive drill rig. Drill rigs are often mounted on big trucks. They use rotary drill bits that chew away at the rock, percussion bits that smash the rock, or, if the ground is soft, large auger bits. Drilled wells can be drilled more than 1,000 feet deep. Often a pump is placed in the well at some depth to push the water up to the surface..Wells and Pumpage
Water Levels in Wells
Groundwater users would find life easier if the water level in the aquifer that supplied their well always stayed the same. Seasonal variations in rainfall and the occasional drought affect the "height" of the underground water level. Withdrawing water from a well causes the water levels around the well to lower. The water level in a well can also be lowered if other wells near it are withdrawing water. When water levels drop below the levels of the pump intakes, then wells will begin to pump air - they will "go dry."
Pumping a well lowers the water level around the well to form a cone of depression in the water table. If the cone of depression extends to other nearby wells, the water level in those wells will be lowered. The cone develops in both shallow water-table and deeper confined-aquifer systems. In the deeper confined-aquifer system, the cone of depression is indicated by a decline in the pressure and the cone spreads over a much larger area than in a water-table system. For a given rate of withdrawal, the cone of depression extends deeper in low-yielding aquifers than in high-yielding ones.
Even though water is present at some depth at almost any location, the success of obtaining an adequate domestic supply (usually 5 gallons per minute) of water from a well depends upon the permeability of the rock. Where permeable materials are near land surface, a shallow well may be adequate. Elsewhere, such as where clayey material directly overlies bedrock, a deep well extending into bedrock may be needed.
Private Wells

Credit: U.S. Environmental Protection Agency
Many people in the United States and worldwide supply their own water for their homes, often in more rural locations that don't have large public-supply water systems to supply water. Here is a basic diagram showing how these wells function. Although this diagram shows a single home, large wells that supply more customers work generally the same.
WELL COMPONENTS
Below are descriptions of the basic components found in a private water well. (Source: National Ground Water Association)
- Well Casing is the tube-shaped structure placed in the well to maintain the well opening from the target ground water to the surface. Along with grout, the casing keeps dirt and excess water out of the well. This helps prevent contaminants from less desirable groundwater from entering the well and mixing with the drinking water. Some states and local governing agencies have laws that require minimum lengths for casing. The most common materials for well casing are carbon steel, plastic, and stainless steel. Local geology often dictates what type of casing can be used.
- Well Caps are placed on top of the well casing to prevent debris, insects, or small animals from getting into the well. Well caps are usually made of aluminum or plastic. They include a vent to control pressure during well pumping.
- Well Screens are attached to the bottom of the casing to prevent too much sediment from entering the well. The most common well screens are continuous slot, slotted pipe, and perforated pipe.
- Pitless Adapter is a connector that allows the pipe carrying water to the surface to remain below the frost line. It ensures that a sanitary and frost-proof seal is maintained.
- Jet Pumps are the most commonly used pumps for shallow wells (depth of 25 feet or less). Jet pumps are mounted above ground and use suction to draw water from the well.
- Submersible Pumps are the most commonly used pumps for deep private wells. The pumping unit is placed inside the well casing and connected to a power source on the surface.
Information on this page is from Ground Water and the Rural Homeowner, Pamphlet, U.S. Geological Survey, 1982, by Roger M. Waller.
Quiz icon made by mynamepong from www.flaticon.com
Want to learn more about groundwater wells? Follow me to the Groundwater Basics and Domestic (Private) Supply Wells websites!
Below are other science topics associated with groundwater wells.
Groundwater Information by Topic
Groundwater Quality Research
Groundwater True/False Quiz
National Water Quality Program
Pesticides in Groundwater
Contamination of Groundwater
Artesian Water and Artesian Wells
Below are publications associated with groundwater wells.
A primer on ground water
Ground water and the rural homeowner
- Overview
Wells are extremely important to all societies. In many places wells provide a reliable and ample supply of water for home uses, irrigation, and industries. Where surface water is scarce, such as in deserts, people couldn't survive and thrive without groundwater, and people use wells to get at underground water.
• Water Science School HOME • Groundwater topics •
Groundwater Wells
Sources/Usage: Some content may have restrictions. Visit Media to see details.You may know that groundwater serves many purposes worldwide. Of course, drinking water and domestic uses of water are major components of those uses. The ways of getting at groundwater differ depending on the local underground conditions. Water may be plentiful just 10 feet below the land surface, or a deep well might have to be drilled many hundreds of feet to get at scarcer water filling the cracks between dense rock particles. Pumps are often needed to push water to the land surface.But this little lad is lucky as his well is located in a place where groundwater is shallow and plentiful. Thus, he, with his parents' help, can just hand-lower the bucket a few feet down and crank the bucket full of water back to the surface. This picture does not show a working well, but wells just like this have served the water needs of people for many centuries and still do today.
Credit: Howard Perlman, USGSThere's a good chance that the average Joe who had to dig a well in ancient Egypt probably did the work with his hands, a shovel, and a bucket. He would have kept digging until he reached the water table, where all the spaces between the rock and dirt particles are filled with water, and water filled the bottom of the hole. Some wells are still dug by hand today, but more modern methods are available.
Wells are extremely important to all societies. In many places wells provide a reliable and ample supply of water for home uses, irrigation, and industries. Where surface water is scarce, such as in deserts,people couldn't survive and thrive without groundwater.
Types of wells
Digging a well by hand is becoming outdated today as automated drilling methods replace manual-labor methods. Modern wells are more often drilled by a truck-mounted drill rig. Still, there are many ways to put in a well — here are some of the common methods.
DUG WELLS
Hacking at the ground with a pick and shovel is one way to dig a well. If the ground is soft and the water table is shallow,then dug wells can work. Historically, dug wells were excavated by hand shovel to below the water table until incoming water exceeded the digger's bailing rate. The well was lined with stones, brick, tile, or other material to prevent collapse, and was covered with a cap of wood, stone, or concrete. They cannot be dug much deeper than the water table — just as you cannot dig a hole very deep when you are at the beach... it keeps filling up with water!
Example of a pump and plumbing configuration used by public water systems.
Credit: Roland Tollett, USGSDug and bored wells have a large diameter and expose a large area to the aquifer. These wells are able to obtain water from less-permeable materials such as very fine sand, silt, or clay. Some disadvantages of this type of well are that they are shallow and lack continuous casing, making them subject to contamination from nearby surface sources, and they go dry during periods of drought if the water table drops below the well bottom.
DRIVEN WELLS
Driven wells are still common today. They are built by driving a small-diameter pipe into soft earth, such as sand or gravel. A screen is usually attached to the bottom of the pipe to filter out sand and other particles. Problems? They can only tap shallow water, and because the source of the water is so close to the surface, contamination from surface pollutants can occur.
DRILLED WELLS
Most modern wells are drilled, which requires a fairly complicated and expensive drill rig. Drill rigs are often mounted on big trucks. They use rotary drill bits that chew away at the rock, percussion bits that smash the rock, or, if the ground is soft, large auger bits. Drilled wells can be drilled more than 1,000 feet deep. Often a pump is placed in the well at some depth to push the water up to the surface..Wells and Pumpage
Water Levels in Wells
Groundwater users would find life easier if the water level in the aquifer that supplied their well always stayed the same. Seasonal variations in rainfall and the occasional drought affect the "height" of the underground water level. Withdrawing water from a well causes the water levels around the well to lower. The water level in a well can also be lowered if other wells near it are withdrawing water. When water levels drop below the levels of the pump intakes, then wells will begin to pump air - they will "go dry."
Pumping a well lowers the water level around the well to form a cone of depression in the water table. If the cone of depression extends to other nearby wells, the water level in those wells will be lowered. The cone develops in both shallow water-table and deeper confined-aquifer systems. In the deeper confined-aquifer system, the cone of depression is indicated by a decline in the pressure and the cone spreads over a much larger area than in a water-table system. For a given rate of withdrawal, the cone of depression extends deeper in low-yielding aquifers than in high-yielding ones.
Even though water is present at some depth at almost any location, the success of obtaining an adequate domestic supply (usually 5 gallons per minute) of water from a well depends upon the permeability of the rock. Where permeable materials are near land surface, a shallow well may be adequate. Elsewhere, such as where clayey material directly overlies bedrock, a deep well extending into bedrock may be needed.
Private Wells
Sources/Usage: Public Domain. Visit Media to see details.A schematic of how a typical single-home domestic water well works.
Credit: U.S. Environmental Protection AgencyMany people in the United States and worldwide supply their own water for their homes, often in more rural locations that don't have large public-supply water systems to supply water. Here is a basic diagram showing how these wells function. Although this diagram shows a single home, large wells that supply more customers work generally the same.
WELL COMPONENTS
Below are descriptions of the basic components found in a private water well. (Source: National Ground Water Association)
- Well Casing is the tube-shaped structure placed in the well to maintain the well opening from the target ground water to the surface. Along with grout, the casing keeps dirt and excess water out of the well. This helps prevent contaminants from less desirable groundwater from entering the well and mixing with the drinking water. Some states and local governing agencies have laws that require minimum lengths for casing. The most common materials for well casing are carbon steel, plastic, and stainless steel. Local geology often dictates what type of casing can be used.
- Well Caps are placed on top of the well casing to prevent debris, insects, or small animals from getting into the well. Well caps are usually made of aluminum or plastic. They include a vent to control pressure during well pumping.
- Well Screens are attached to the bottom of the casing to prevent too much sediment from entering the well. The most common well screens are continuous slot, slotted pipe, and perforated pipe.
- Pitless Adapter is a connector that allows the pipe carrying water to the surface to remain below the frost line. It ensures that a sanitary and frost-proof seal is maintained.
- Jet Pumps are the most commonly used pumps for shallow wells (depth of 25 feet or less). Jet pumps are mounted above ground and use suction to draw water from the well.
- Submersible Pumps are the most commonly used pumps for deep private wells. The pumping unit is placed inside the well casing and connected to a power source on the surface.
Learn the basics about water using our Water Primers!A Primer on Water (PDF)A Primer on Ground Water (PDF)Ground water and the Rural Homeowner Do you think you know about groundwater?Take our Groundwater true/false quiz, part of our Activity Center. Information on this page is from Ground Water and the Rural Homeowner, Pamphlet, U.S. Geological Survey, 1982, by Roger M. Waller.
Quiz icon made by mynamepong from www.flaticon.com
Want to learn more about groundwater wells? Follow me to the Groundwater Basics and Domestic (Private) Supply Wells websites!
- Science
Below are other science topics associated with groundwater wells.
Groundwater Information by Topic
Groundwater is one of our most valuable resources—even though you probably never see it or even realize it is there. There is water somewhere beneath your feet no matter where on Earth you live. Groundwater starts as precipitation, just as surface water does, and once water penetrates the ground, it continues moving, sometimes quickly and sometimes very slowly. Eventually groundwater emerges back...Groundwater Quality Research
Every day, millions of gallons of groundwater are pumped to supply drinking water for about 140 million people, almost one-half of the Nation’s population. Learn about the quality and availability of groundwater for drinking, where and why groundwater quality is degraded, and where groundwater quality is changing.Groundwater True/False Quiz
How much do you know about the water below your feet? Take our Groundwater True/False Quiz and find out.National Water Quality Program
The National Water Quality Program seeks to answer four questions regarding the quality of our freshwater resources: 1) What is the quality of the Nation's streams and groundwater? 2) How is water quality changing over time? 3) How do natural factors and human activities affect water quality? 4) How will water quality change in response to future changes in climate and human activities?Pesticides in Groundwater
Commercial pesticide applicators, farmers, and homeowners apply about 1 billion pounds of pesticides annually to agricultural land, non-crop land, and urban areas throughout the United States. The use of pesticides has helped to make the United States the largest producer of food in the world and has provided other benefits, but has also been accompanied by concerns about their potential adverse...Contamination of Groundwater
Groundwater will normally look clear and clean because the ground naturally filters out particulate matter. But did you know that natural and human-induced chemicals can be found in groundwater even if appears to be clean? Below is a list of some contaminants that can occur in groundwater.Artesian Water and Artesian Wells
Artesian water is really not different from other groundwater, except for the fact that it flows to the land surface because pressure in the rocks underground force it to the surface. But, having water flow to the surface naturally is a handy way to tap groundwater resources. - Publications
Below are publications associated with groundwater wells.
A primer on ground water
Most of us don't have to look for water. We grew up either in big cities where there was a public water supply, or in small towns or on farms where the water came from wells. But there are some people to whom finding a new supply of water is vitally important.AuthorsHelene L. Baldwin, C. L. McGuinnessGround water and the rural homeowner
As the salesmen sang in the musical The Music Man, "You gotta know the territory." This saying is also true when planning to buy or build a house. Learn as much as possible about the land, the water supply, and the septic system of the house before buying or building. Do not just look at the construction aspects or the beauty of the home and surroundings. Be sure to consider the environmental condAuthorsRoger M. Waller