What is Groundwater?

Mary McMahon
Mary McMahon

Groundwater is potable water which is stored underground. It can be confined, which means that a deposit of water is surrounded by nonpermeable rock, or unconfined, in which case it is surrounded by permeable rock, gravel, soil, and other materials. Around 20% of the world's freshwater is groundwater, and groundwater makes up a significant portion of the potable water consumed worldwide, with up to 50% of some populations relying on groundwater for drinking, bathing, industrial production, and a variety of other tasks.

Runoff from rivers and streams ends up in the groundwater.
Runoff from rivers and streams ends up in the groundwater.

A number of things can lead to the development of a groundwater formation. Rainfall, for example, drains into the ground and into deposits of groundwater, and runoff from rivers, streams, and lakes also winds up in the world's groundwater. Groundwater levels are also supplemented by snow melt and melting glaciers, and the supply may be seasonal, depending on high rainfall and snow melt to supply groundwater in the spring, with supplies which dwindle in the late summer and fall.

Groundwater supplies the drinking water to many people in the world.
Groundwater supplies the drinking water to many people in the world.

When a deposit of groundwater can be used sustainably as a water source by humans, it is known as an aquifer. Many people try to seek out contained aquifers, because the quality of the groundwater tends to be better when it is contained. Contained aquifers are at less risk of pollution, making the water safer to drink. In an unconfined aquifer, water can be tainted with chemicals, biological agents, feces, and other materials which are not desirable in drinking water.

One of the most common ways to access a deposit of groundwater is a well. Wells are drilled down into deposits of groundwater and pressurized so that the water bubbles to the surface, allowing people to use it. People can also dip buckets into wells to collect the water, as has been done historically. It is also possible to access groundwater through springs, which periodically bubble up with fresh groundwater. Historically, settlements have often been constructed around springs, to save the cost of sinking a well to supply a community.

Sometimes, a water source dries up. This happens when the aquifer is so depleted that it cannot provide water anymore. Sometimes, drilling deeper can solve the problem, by accessing the bottom of the aquifer. In other instances, a well or spring may refill itself at a later juncture, after the aquifer has had a chance to recover. Abandoned wells are viewed as a safety risk in some areas, since the lack of maintenance can result in an uncovered well which people or animals could fall into.

Industrial wastewater treatment processes must remove contaminants before releasing the water into the environment.
Industrial wastewater treatment processes must remove contaminants before releasing the water into the environment.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


I can remember a severely dry summer in which my city's water supply dried up. We went for so long without rain, and the scorching temperatures led to the quick evaporation of what little water remained in the aquifer. Everyone's water bills soared, and the city was in an uproar.

They had to tap into a neighboring city's water source, and people in that city were upset, because they hadn't seen much rain in awhile, either. Though they had more groundwater than we did, they knew that we could soon deplete their source.

There really was no good solution to the problem. Many people had to move because of the ridiculously high water bills, and the ones that remained were not happy. Lots of people stopped drinking water and switched to sodas to save a bit of money.


@Perdido – Unpolluted groundwater is the best kind. I get my drinking water from a nearby spring, and I cannot stand to drink bottled water after having tasted the purity of the groundwater.

I live in a hilly area near the woods and a clear stream. Several natural springs exist in this region, and I take advantage of them. I go out to the spring with an empty case of bottles, and I bottle my own spring water.

Whenever I am getting low on water, I go out and do this. I find it so refreshing. I would rather drink this groundwater than sodas or tea, and the best part is that it's free!


I have a fear of those old groundwater wells. A kid in my neighborhood fell into one while playing, and it took authorities an entire day to rescue her.

The well was so deep, dark, and narrow that it posed difficulties to rescuers. I know that poor kid had to be terrified beyond belief.

I have a fear of the dark, and a well would be about the darkest place anyone could encounter. No sunlight could permeate that deep chasm, and you would have nothing but your fears to torment you.

Everyone was so relieved when they finally brought her to the surface. They capped off that well and made it illegal for anyone to have uncovered wells in the neighborhood.


My elderly neighbors have depended on a well in their backyard for water for all of their lives. I have drunk their water before, and it has a sweetness that you don't find in most tap water anymore.

My neighbor tasted tap water at her daughter's house, and she nearly choked on it. Since she had become accustomed to fresh groundwater with no chemicals added, she could really taste the chlorine in her daughter's water. She told her that it can't be good for her health.

Honestly, after tasting well water, I could barely tolerate the tap water in my own house. So, I got a water filter to attach to the sink. It tastes much better now.

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