Scientists monitoring a shallow groundwater well in Los Planes watershed, Baja California Sur, Mexico. (Laura Norman, USGS)
How important is groundwater?
Groundwater, which is in aquifers below the surface of the Earth, is one of the Nation's most important natural resources. Groundwater is the source of about 37 percent of the water that county and city water departments supply to households and businesses (public supply). It provides drinking water for more than 90 percent of the rural population who do not get their water delivered to them from a county/city water department or private water company.
Even some major cities, such as San Antonio, Texas, rely solely on groundwater for all their needs. About 42 percent of the water used for irrigation comes from groundwater.
Withdrawals of groundwater are expected to rise as the population increases and available sites for surface reservoirs become more limited.
Learn more: Groundwater Use
Related
If the ground filters water, is groundwater always clean?
Water drawn from a well was once precipitation that fell onto Earth's surface. It seeped into the ground and, over time, occupied the porous space in some subsurface material. Big particles that are in surface streams, such as leaf chunks, will not be seen in groundwater. So, yes, big particles are filtered out by the ground, along with some minerals and chemicals that are too small to see. But...
What is groundwater?
Groundwater is water that exists underground in saturated zones beneath the land surface. The upper surface of the saturated zone is called the water table. Contrary to popular belief, groundwater does not form underground rivers. It fills the pores and fractures in underground materials such as sand, gravel, and other rock, much the same way that water fills a sponge. If groundwater flows...
Where can I find detailed sampling methods for surface water and groundwater?
The National Field Manual for the Collection of Water-Quality Data (National Field Manual) provides guidelines and standard procedures for USGS personnel who collect data used to assess the quality of the Nation’s surface water and groundwater resources. The manual is published as separate chapters. Learn more: Techniques of Water-Resources Investigations Reports
How frequently are volatile organic compounds (VOCs) detected in groundwater?
Volatile organic compounds (VOCs), which are widely used in the manufacture of many products including refrigerants, plastics, adhesives, paints, and petroleum products, have been detected in about one-third of the wells sampled by the National Water-Quality Assessment (NAWQA) Program of the USGS. Chloroform and other trihalomethanes, the most commonly detected compounds, were found in about 9...
Where can I get my well water tested?
Some counties offer free well water testing, so check with your county first. If they don't, use this EPA website to find a list of state-certified laboratories in your area that do water testing, or contact your county or state health department or your State Certification Officer for assistance. Prices will vary depending on the laboratory and the test(s), but most people consider the cost to be...
How can I find the depth to the water table in a specific location?
The depth to the water table can change (rise or fall) depending on the time of year. During the late winter and spring when accumulated snow starts to melt and spring rainfall is plentiful, water on the surface infiltrates into the ground and the water table rises. When water-loving plants start to grow again in the spring and precipitation gives way to hot, dry summers, the water table falls...
What is the Ground Water Atlas of the United States?
This Ground Water Atlas of the United States is a series of USGS publications that describe the location, the extent, and the geologic and hydrologic characteristics of the important aquifers of the Nation. The series consists of 13 chapters that describe the regional groundwater resources that collectively cover 50 States, Puerto Rico, and the U.S. Virgin Islands. Learn more: Principal Aquifers...
How much natural water is there?
Earth is estimated to hold about 1,386,000,000 cubic kilometers of water. The breakdown of where all that water resides is estimated as follows: Oceans (saline) 1,338,000,000 cubic kilometers Ice caps and glaciers (fresh) 24,064,000 cubic kilometers Groundwater (fresh and saline) 23,400,000 cubic kilometers Streams, lakes, swamps (fresh) 104,590 cubic kilometers Lakes (saline) 85,400 cubic...
How much water is used by people in the United States?
Since 1950, the USGS has collected and analyzed water-use data for the United States and its Territories. That data is revised every 5 years. As of 2015, the United States uses 322 billion gallons of water per day (Bgal/day). The three largest water-use categories were irrigation (118 Bgal/day), thermoelectric power (133 Bgal/day), and public supply (39 Bgal/day), cumulatively accounting for 90...
Monitoring a shallow groundwater well in Los Planes watershed, Baja California Sur, Mexico
Scientists monitoring a shallow groundwater well in Los Planes watershed, Baja California Sur, Mexico. (Laura Norman, USGS)
Physical Scientist Shannon Fisher taking a water level measurement with a calibrated electric tape at the monthly discrete groundwater observation well located in Foster, Rhode Island
linkPhysical Scientist Shannon Fisher taking a water level measurement with a calibrated electric tape at the monthly discrete groundwater observation well located in Foster, Rhode Island. (Station ID#: 414420071422301 RI-FOW 40)
Winter 2024 Photo Contest: Sam Banas, Honorable Mention category
Physical Scientist Shannon Fisher taking a water level measurement with a calibrated electric tape at the monthly discrete groundwater observation well located in Foster, Rhode Island
linkPhysical Scientist Shannon Fisher taking a water level measurement with a calibrated electric tape at the monthly discrete groundwater observation well located in Foster, Rhode Island. (Station ID#: 414420071422301 RI-FOW 40)
Winter 2024 Photo Contest: Sam Banas, Honorable Mention category
Conceptualization of the factors that affect groundwater recharge in oceanic islands.
Conceptualization of the factors that affect groundwater recharge in oceanic islands.
Conceptualization of the factors that affect groundwater recharge in oceanic islands.
Groundwater Well in Mill Creek Basin in Cape Cod National Seashore
A Geoscientist-in-the-Park Guest Scientist for the National Park Service services a USGS groundwater well located within the Mill Creek basin near the Herring River in Wellfleet, Massachusetts.
A Geoscientist-in-the-Park Guest Scientist for the National Park Service services a USGS groundwater well located within the Mill Creek basin near the Herring River in Wellfleet, Massachusetts.
Land Subsidence near El Nido, CA
National Geodetic Survey vertical control bench mark W990 CADWR in Merced County, California. W 990 CADWR is on the Mariposa Bypass Bridge on Washington Rd. This is one of several bench mark locations used to help measure the largest recent subsidence in the area using repeat surveys.
National Geodetic Survey vertical control bench mark W990 CADWR in Merced County, California. W 990 CADWR is on the Mariposa Bypass Bridge on Washington Rd. This is one of several bench mark locations used to help measure the largest recent subsidence in the area using repeat surveys.
Land Subsidence near El Nido, CA
National Geodetic Survey vertical control bench mark H1235 RESET in Merced County, California. H 1235 RESET is in the median of State Highway 15. This is one of several bench mark locations used to help measure the largest recent subsidence in the area using repeat surveys.
National Geodetic Survey vertical control bench mark H1235 RESET in Merced County, California. H 1235 RESET is in the median of State Highway 15. This is one of several bench mark locations used to help measure the largest recent subsidence in the area using repeat surveys.
PubTalk 11/2014 — Water, Nuts, and the Nation's Fruit Bowl
California's Central Valley Hydrologic Science
by Claudia Faunt, USGS Hydrologist
California's Central Valley Hydrologic Science
by Claudia Faunt, USGS Hydrologist
PubTalk 9/2011 — Tracking the Nation's Groundwater Reserves
--issues facing current and future water supplies
by William Alley, USGS Office of Groundwater
--issues facing current and future water supplies
by William Alley, USGS Office of Groundwater
USGS employee sampling an urban groundwater well
USGS employee sampling an urban groundwater well. Photo from USGS circular 1352 "Water quality in the Glacial Aquifer System, Northern United States, 1993 - 2009.
USGS employee sampling an urban groundwater well. Photo from USGS circular 1352 "Water quality in the Glacial Aquifer System, Northern United States, 1993 - 2009.
Irrigation water from a groundwater well on a rice crop field
Irrigation water from a groundwater well on a rice crop field. Photo from USGS circular 1356 "Water Quality in the Mississippi Embayment-Texas Coastal Uplands Aquifer System and Mississippi River Valley Alluvial Aquifer, South-Central United States, 1994-2008."
Irrigation water from a groundwater well on a rice crop field. Photo from USGS circular 1356 "Water Quality in the Mississippi Embayment-Texas Coastal Uplands Aquifer System and Mississippi River Valley Alluvial Aquifer, South-Central United States, 1994-2008."
Irrigation groundwater well
Irrigation groundwater well. Photo from USGS circular 1356 "Water Quality in the Mississippi Embayment-Texas Coastal Uplands Aquifer System and Mississippi River Valley Alluvial Aquifer, South-Central United States, 1994-2008."
Irrigation groundwater well. Photo from USGS circular 1356 "Water Quality in the Mississippi Embayment-Texas Coastal Uplands Aquifer System and Mississippi River Valley Alluvial Aquifer, South-Central United States, 1994-2008."
Related
If the ground filters water, is groundwater always clean?
Water drawn from a well was once precipitation that fell onto Earth's surface. It seeped into the ground and, over time, occupied the porous space in some subsurface material. Big particles that are in surface streams, such as leaf chunks, will not be seen in groundwater. So, yes, big particles are filtered out by the ground, along with some minerals and chemicals that are too small to see. But...
What is groundwater?
Groundwater is water that exists underground in saturated zones beneath the land surface. The upper surface of the saturated zone is called the water table. Contrary to popular belief, groundwater does not form underground rivers. It fills the pores and fractures in underground materials such as sand, gravel, and other rock, much the same way that water fills a sponge. If groundwater flows...
Where can I find detailed sampling methods for surface water and groundwater?
The National Field Manual for the Collection of Water-Quality Data (National Field Manual) provides guidelines and standard procedures for USGS personnel who collect data used to assess the quality of the Nation’s surface water and groundwater resources. The manual is published as separate chapters. Learn more: Techniques of Water-Resources Investigations Reports
How frequently are volatile organic compounds (VOCs) detected in groundwater?
Volatile organic compounds (VOCs), which are widely used in the manufacture of many products including refrigerants, plastics, adhesives, paints, and petroleum products, have been detected in about one-third of the wells sampled by the National Water-Quality Assessment (NAWQA) Program of the USGS. Chloroform and other trihalomethanes, the most commonly detected compounds, were found in about 9...
Where can I get my well water tested?
Some counties offer free well water testing, so check with your county first. If they don't, use this EPA website to find a list of state-certified laboratories in your area that do water testing, or contact your county or state health department or your State Certification Officer for assistance. Prices will vary depending on the laboratory and the test(s), but most people consider the cost to be...
How can I find the depth to the water table in a specific location?
The depth to the water table can change (rise or fall) depending on the time of year. During the late winter and spring when accumulated snow starts to melt and spring rainfall is plentiful, water on the surface infiltrates into the ground and the water table rises. When water-loving plants start to grow again in the spring and precipitation gives way to hot, dry summers, the water table falls...
What is the Ground Water Atlas of the United States?
This Ground Water Atlas of the United States is a series of USGS publications that describe the location, the extent, and the geologic and hydrologic characteristics of the important aquifers of the Nation. The series consists of 13 chapters that describe the regional groundwater resources that collectively cover 50 States, Puerto Rico, and the U.S. Virgin Islands. Learn more: Principal Aquifers...
How much natural water is there?
Earth is estimated to hold about 1,386,000,000 cubic kilometers of water. The breakdown of where all that water resides is estimated as follows: Oceans (saline) 1,338,000,000 cubic kilometers Ice caps and glaciers (fresh) 24,064,000 cubic kilometers Groundwater (fresh and saline) 23,400,000 cubic kilometers Streams, lakes, swamps (fresh) 104,590 cubic kilometers Lakes (saline) 85,400 cubic...
How much water is used by people in the United States?
Since 1950, the USGS has collected and analyzed water-use data for the United States and its Territories. That data is revised every 5 years. As of 2015, the United States uses 322 billion gallons of water per day (Bgal/day). The three largest water-use categories were irrigation (118 Bgal/day), thermoelectric power (133 Bgal/day), and public supply (39 Bgal/day), cumulatively accounting for 90...
Monitoring a shallow groundwater well in Los Planes watershed, Baja California Sur, Mexico
Scientists monitoring a shallow groundwater well in Los Planes watershed, Baja California Sur, Mexico. (Laura Norman, USGS)
Scientists monitoring a shallow groundwater well in Los Planes watershed, Baja California Sur, Mexico. (Laura Norman, USGS)
Physical Scientist Shannon Fisher taking a water level measurement with a calibrated electric tape at the monthly discrete groundwater observation well located in Foster, Rhode Island
linkPhysical Scientist Shannon Fisher taking a water level measurement with a calibrated electric tape at the monthly discrete groundwater observation well located in Foster, Rhode Island. (Station ID#: 414420071422301 RI-FOW 40)
Winter 2024 Photo Contest: Sam Banas, Honorable Mention category
Physical Scientist Shannon Fisher taking a water level measurement with a calibrated electric tape at the monthly discrete groundwater observation well located in Foster, Rhode Island
linkPhysical Scientist Shannon Fisher taking a water level measurement with a calibrated electric tape at the monthly discrete groundwater observation well located in Foster, Rhode Island. (Station ID#: 414420071422301 RI-FOW 40)
Winter 2024 Photo Contest: Sam Banas, Honorable Mention category
Conceptualization of the factors that affect groundwater recharge in oceanic islands.
Conceptualization of the factors that affect groundwater recharge in oceanic islands.
Conceptualization of the factors that affect groundwater recharge in oceanic islands.
Groundwater Well in Mill Creek Basin in Cape Cod National Seashore
A Geoscientist-in-the-Park Guest Scientist for the National Park Service services a USGS groundwater well located within the Mill Creek basin near the Herring River in Wellfleet, Massachusetts.
A Geoscientist-in-the-Park Guest Scientist for the National Park Service services a USGS groundwater well located within the Mill Creek basin near the Herring River in Wellfleet, Massachusetts.
Land Subsidence near El Nido, CA
National Geodetic Survey vertical control bench mark W990 CADWR in Merced County, California. W 990 CADWR is on the Mariposa Bypass Bridge on Washington Rd. This is one of several bench mark locations used to help measure the largest recent subsidence in the area using repeat surveys.
National Geodetic Survey vertical control bench mark W990 CADWR in Merced County, California. W 990 CADWR is on the Mariposa Bypass Bridge on Washington Rd. This is one of several bench mark locations used to help measure the largest recent subsidence in the area using repeat surveys.
Land Subsidence near El Nido, CA
National Geodetic Survey vertical control bench mark H1235 RESET in Merced County, California. H 1235 RESET is in the median of State Highway 15. This is one of several bench mark locations used to help measure the largest recent subsidence in the area using repeat surveys.
National Geodetic Survey vertical control bench mark H1235 RESET in Merced County, California. H 1235 RESET is in the median of State Highway 15. This is one of several bench mark locations used to help measure the largest recent subsidence in the area using repeat surveys.
PubTalk 11/2014 — Water, Nuts, and the Nation's Fruit Bowl
California's Central Valley Hydrologic Science
by Claudia Faunt, USGS Hydrologist
California's Central Valley Hydrologic Science
by Claudia Faunt, USGS Hydrologist
PubTalk 9/2011 — Tracking the Nation's Groundwater Reserves
--issues facing current and future water supplies
by William Alley, USGS Office of Groundwater
--issues facing current and future water supplies
by William Alley, USGS Office of Groundwater
USGS employee sampling an urban groundwater well
USGS employee sampling an urban groundwater well. Photo from USGS circular 1352 "Water quality in the Glacial Aquifer System, Northern United States, 1993 - 2009.
USGS employee sampling an urban groundwater well. Photo from USGS circular 1352 "Water quality in the Glacial Aquifer System, Northern United States, 1993 - 2009.
Irrigation water from a groundwater well on a rice crop field
Irrigation water from a groundwater well on a rice crop field. Photo from USGS circular 1356 "Water Quality in the Mississippi Embayment-Texas Coastal Uplands Aquifer System and Mississippi River Valley Alluvial Aquifer, South-Central United States, 1994-2008."
Irrigation water from a groundwater well on a rice crop field. Photo from USGS circular 1356 "Water Quality in the Mississippi Embayment-Texas Coastal Uplands Aquifer System and Mississippi River Valley Alluvial Aquifer, South-Central United States, 1994-2008."
Irrigation groundwater well
Irrigation groundwater well. Photo from USGS circular 1356 "Water Quality in the Mississippi Embayment-Texas Coastal Uplands Aquifer System and Mississippi River Valley Alluvial Aquifer, South-Central United States, 1994-2008."
Irrigation groundwater well. Photo from USGS circular 1356 "Water Quality in the Mississippi Embayment-Texas Coastal Uplands Aquifer System and Mississippi River Valley Alluvial Aquifer, South-Central United States, 1994-2008."
Updated Date: January 15, 2025