A water molecule consists of two hydrogen atoms and one oxygen atom
An illustration showing groundwater in aquifers (in blue) (1, 5 and 6) below the water table (4), and three different wells (7, 8 and 9) dug to reach it.
The three common states of matter
Dzherelo, a common source of drinking water in a Ukrainian village
Phase diagram of water (simplified)
The entire surface water flow of the Alapaha River near Jennings, Florida, going into a sinkhole leading to the Floridan Aquifer groundwater
Tetrahedral structure of water
Groundwater may be extracted through a water well
Model of hydrogen bonds (1) between molecules of water
Diagram of a water balance of the aquifer
Water cycle
Iron (III) oxide staining (after water capillary rise in a wall) caused by oxidation of dissolved iron (II) and its subsequent precipitation, from an unconfined aquifer in karst topography. Perth, Western Australia.
Overview of photosynthesis (green) and respiration (red)
Groundwater withdrawal rates from the Ogallala Aquifer in the Central United States
Water fountain
Center-pivot irrigated fields in Kansas covering hundreds of square miles watered by the Ogallala Aquifer
An environmental science program – a student from Iowa State University sampling water
Total water withdrawals for agricultural, industrial and municipal purposes per capita, measured in cubic metres (m³) per year in 2010
A young girl drinking bottled water
Water availability: the fraction of the population using improved water sources by country
Roadside fresh water outlet from glacier, Nubra
Hazard symbol for non-potable water
Water is used for fighting wildfires.
San Andrés island, Colombia
Water can be used to cook foods such as noodles
Sterile water for injection
Band 5 ALMA receiver is an instrument specifically designed to detect water in the universe.
South polar ice cap of Mars during Martian south summer 2000
An estimate of the proportion of people in developing countries with access to potable water 1970–2000
People come to Inda Abba Hadera spring (Inda Sillasie, Ethiopia) to wash in holy water
Icosahedron as a part of Spinoza monument in Amsterdam.
Water requirement per tonne of food product
Irrigation of field crops
Specific heat capacity of water

Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations.

- Groundwater

Small portions of water occur as groundwater (1.7%), in the glaciers and the ice caps of Antarctica and Greenland (1.7%), and in the air as vapor, clouds (consisting of ice and liquid water suspended in air), and precipitation (0.001%).

- Water
A water molecule consists of two hydrogen atoms and one oxygen atom

10 related topics

Alpha

Water cycle

Time-mean precipitation and evaporation as a function of latitude as simulated by an aqua-planet version of an atmospheric GCM (GFDL's AM2.1) with a homogeneous “slab-ocean” lower boundary (saturated surface with small heat capacity), forced by annual mean insolation.
Global map of annual mean evaporation minus precipitation by latitude-longitude
Relationship between impervious surfaces and surface runoff
Diagram of the water cycle
Natural water cycle

The water cycle, also known as the hydrologic cycle or the hydrological cycle, is a biogeochemical cycle that describes the continuous movement of water on, above and below the surface of the Earth.

Runoff and water emerging from the ground (groundwater) may be stored as freshwater in lakes.

Schematic of an aquifer showing confined zones, groundwater travel times, a spring and a well

Aquifer

Schematic of an aquifer showing confined zones, groundwater travel times, a spring and a well
An aquifer cross-section. This diagram shows two aquifers with one aquitard (a confining or impermeable layer) between them, surrounded by the bedrock aquiclude, which is in contact with a gaining stream (typical in humid regions). The water table and unsaturated zone are also illustrated.
Water in porous aquifers slowly seeps through pore spaces between sand grains
Water in karst aquifers flows through open conduits where water flows as underground streams
Map of major US aquifers by rock type
Texas blind salamander found in Edwards Aquifer

An aquifer is an underground layer of water-bearing permeable rock, rock fractures or unconsolidated materials (gravel, sand, or silt).

Groundwater from aquifers can be extracted using a water well.

Runoff flowing into a stormwater drain

Surface runoff

Runoff flowing into a stormwater drain
Surface runoff from a hillside after soil is saturated
Precipitation washing contaminates into local streams
Urban surface water runoff
Willow hedge strengthened with fascines for the limitation of runoff, north of France.
Soil erosion by water on intensively-tilled farmland.
Farmland runoff
Runoff holding ponds (Uplands neighborhood of North Bend, Washington)

Surface runoff (also known as overland flow) is the flow of water occurring on the ground surface when excess rainwater, stormwater, meltwater, or other sources, can no longer sufficiently rapidly infiltrate in the soil.

Increased runoff reduces groundwater recharge, thus lowering the water table and making droughts worse, especially for agricultural farmers and others who depend on the water wells.

Boy drinks from a tap at a NEWAH WASH water project in Puware Shikhar, Udayapur District, Nepal.

Hydrogeology

Boy drinks from a tap at a NEWAH WASH water project in Puware Shikhar, Udayapur District, Nepal.
Checking wells
Boy under a waterfall in Phu Sang National Park, Thailand.
Demänovská Cave of Liberty, "Emerald Lake"
Karst spring (Cuneo, Piemonte, Italy)
Painting by Ivan Aivazovsky (1841)
A piezometer is a device used to measure the hydraulic head of groundwater.
A water drop.
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[Left] High porosity, well sorted [Right] Low porosity, poorly sorted
Illustration of seasonal fluctuations in the water table.
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Henry Darcy, whose work set the foundation of quantitative hydrogeology
Geometry of a partially penetrating well drainage system in an anisotropic layered aquifer
Relative groundwater travel times.
A water well in Kerala, India.

Hydrogeology (hydro- meaning water, and -geology meaning the study of the Earth) is the area of geology that deals with the distribution and movement of groundwater in the soil and rocks of the Earth's crust (commonly in aquifers).

Hydrogeology is an interdisciplinary subject; it can be difficult to account fully for the chemical, physical, biological and even legal interactions between soil, water, nature and society.

An inland lake, an example of surface water

Surface water

An inland lake, an example of surface water
The entire surface water flow of the Alapaha River near Jennings, Florida going into a sinkhole leading to the Floridan Aquifer groundwater.
A stream gauge used to measure surface water.

Surface water is water located on top of the Earth's surface, and may also be referred to as blue water.

Levels of surface water lessen as a result of evaporation as well as water moving into the ground becoming ground-water.

Visualisation of the distribution (by volume) of water on Earth. Each tiny cube (such as the one representing biological water) corresponds to approximately 1400 cubic km of water, with a mass of approximately 1.4 trillion tonnes (235000 times that of the Great Pyramid of Giza or 8 times that of Lake Kariba, arguably the heaviest man-made object). The entire block comprises 1 million tiny cubes.

Fresh water

Visualisation of the distribution (by volume) of water on Earth. Each tiny cube (such as the one representing biological water) corresponds to approximately 1400 cubic km of water, with a mass of approximately 1.4 trillion tonnes (235000 times that of the Great Pyramid of Giza or 8 times that of Lake Kariba, arguably the heaviest man-made object). The entire block comprises 1 million tiny cubes.
A graphical distribution of the locations of water on Earth. Only 3% of the Earth's water is fresh water. Most of it is in icecaps and glaciers (69%) and groundwater (30%), while all lakes, rivers and swamps combined only account for a small fraction (0.3%) of the Earth's total freshwater reserves.

Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids.

Fresh water may encompass frozen and meltwater in ice sheets, ice caps, glaciers, snowfields and icebergs, natural precipitations such as rainfall, snowfall, hail/sleet and graupel, and surface runoffs that form inland bodies of water such as wetlands, ponds, lakes, rivers, streams, as well as groundwater contained in aquifers, subterranean rivers and lakes.

A, B, and C represent the soil profile, a notation firstly coined by Vasily Dokuchaev (1846–1903), the father of pedology. Here, A is the topsoil; B is a regolith; C is a saprolite (a less-weathered regolith); the bottom-most layer represents the bedrock.

Soil

Mixture of organic matter, minerals, gases, liquids, and organisms that together support life.

Mixture of organic matter, minerals, gases, liquids, and organisms that together support life.

A, B, and C represent the soil profile, a notation firstly coined by Vasily Dokuchaev (1846–1903), the father of pedology. Here, A is the topsoil; B is a regolith; C is a saprolite (a less-weathered regolith); the bottom-most layer represents the bedrock.
Surface-water-gley developed in glacial till in Northern Ireland
Soil profile: Darkened topsoil and reddish subsoil layers are typical of humid subtropical climate regions.
Desertification
Erosion control

Soil consists of a solid phase of minerals and organic matter (the soil matrix), as well as a porous phase that holds gases (the soil atmosphere) and water (the soil solution).

Capillary action is responsible for moving groundwater from wet regions of the soil to dry areas.

A dug well in a village in Faryab Province, Afghanistan

Well

A dug well in a village in Faryab Province, Afghanistan
The difference between a well and a cistern is in the source of the water: a cistern collects rainwater where a well draws from groundwater.
Camel drawing water from a well, Djerba island, Tunisia, 1960
A Chinese ceramic model of a well with a water pulley system, excavated from a tomb of the Han Dynasty (202 BC – 220 AD) period
Water well near Simaisma, eastern Qatar
Leather bucket used for the water well
Well, Historical Village, Bhaini Sahib, Ludhiana, Punjab, India
View into a hand-dug well cased with concrete rings. Ouelessebougou, Mali.
A dug well in a village in Kerala, India
Cable tool water well drilling rig in Kimball, West Virginia
Water well drilling in Ein Hemed, near Jerusalem circa 1964
Water well types
An old-fashioned water well in the countryside of Utajärvi, Finland
Waterborne diseases can be spread via a well which is contaminated with fecal pathogens from pit latrines.
Man cleaning a well in Yaoundé, Cameroon
Hand pump to pump water from a well in a village near Chennai in India, where the well water might be polluted by nearby pit latrines
Water use, Tacuinum Sanitatis, Biblioteca Casanatense (14th century)
An automated water well system powered by a jet-pump
An automated water well system powered by a submersible pump
A water well system with a cistern
A water well system with a pressurized cistern
A section of a stainless steel screen well
Diagram of a water well partially filled to level z with the top of the aquifer at zT

A well is an excavation or structure created in the ground by digging, driving, or drilling to access liquid resources, usually water.

The oldest and most common kind of well is a water well, to access groundwater in underground aquifers.

A girl collects clean water from a communal water supply in Kawempe, Uganda.

Water supply

A girl collects clean water from a communal water supply in Kawempe, Uganda.
Engine room of municipal water works in Toledo, Ohio, 1908
1880s model of pumping engine, in Herne Bay Museum
Cape Town water crisis warning, July 2018
The sole water supply of this section of Wilder, Tennessee, 1942
A typical residential water meter
Water supplied by a truck in Kolhapur, Maharashtra, India
Shipot, a common source of drinking water in Dzyhivka, Ukraine
Wasserkunst and fountain from 1602 in Wismar, Germany. It's an example of pre-industrialization waterworks and fountain.

Water supply is the provision of water by public utilities, commercial organisations, community endeavors or by individuals, usually via a system of pumps and pipes.

Water supply systems get water from a variety of locations after appropriate treatment, including groundwater (aquifers), surface water (lakes and rivers), and the sea through desalination.

Global values of water resources and human water use (excluding Antarctica). Water resources 1961-90, water use around 2000. Computed by the global freshwater model WaterGAP.

Water resources

Global values of water resources and human water use (excluding Antarctica). Water resources 1961-90, water use around 2000. Computed by the global freshwater model WaterGAP.
Lake Chungará and Parinacota volcano in northern Chile
Relative groundwater travel times in the subsurface
Total renewable freshwater resources of the world, in mm/yr ( 1 mm is equivalent to 1 l of water per m²) (long-term average for the years 1961-1990). Resolution is 0.5° longitude x 0.5° latitude (equivalent to 55 km x 55 km at the equator). Computed by the global freshwater model WaterGAP.
A power plant in Poland
Drinking water
Polluted water
Typical urban water cycle depicting drinking water purification and municipal sewage treatment systems. Source: U.S. Environmental Protection Agency, "Primer for Municipal Wastewater Treatment Systems." EPA 832-R-04-001. p. 7.
Panorama of a natural wetland (Sinclair Wetlands, New Zealand)

Water resources are natural resources of water that are potentially useful for humans, for example as a source of drinking water supply or irrigation water.

Natural sources of fresh water include surface water, under river flow, groundwater and frozen water.