# What is Groundwater? - Definition & Explanation

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

### You're on a roll. Keep up the good work!

Replay
Your next lesson will play in 10 seconds
• 0:02 What Is Groundwater?
• 0:52 Porosity & Permeability
• 2:06 Aquifer
• 2:33 Issues with Groundwater
• 3:31 Lesson Summary
Timeline
Autoplay
Autoplay
Create an account to start this course today
Try it free for 5 days!

#### Recommended Lessons and Courses for You

Lesson Transcript
Instructor: Jeff Fennell

Jeff has a master's in engineering and has taught Earth science both domestically and internationally.

Groundwater accounts for up to 20% of all the fresh water on Earth. This lesson will explain what ground water is and its important aspects. Once you've finished the lesson, test your understanding with a quiz.

## What Is Groundwater?

The simplest definition of groundwater is that it is water that is underground. Of all the fresh water on Earth, about 20% is groundwater. As water seeps into the ground, it continues downward due to gravity until the surrounding ground is saturated with water.

As it moves, water takes up the available spaces between particles underground and moves in the direction of least pressure. When you have groundwater, you have a water table, which is the line where saturated and unsaturated layers meet. If you know how a well works, you may know about water tables because in order for a well to be able to pump water, it must be as deep as the water table.

Now, let's talk about some other factors related to groundwater.

## Porosity and Permeability

The ability for the ground to hold water depends on two main factors, porosity and permeability.

Porosity is the amount of free space within a material. In the case of groundwater, that material is the ground. Imagine pouring water onto sand at the beach. It will sink right in and that's because sand has high porosity. Lots of free space inside it to hold the water. On the other hand, if you pour water onto a sidewalk, it will stay there until it evaporates away. That's because cement has very low porosity. It's very tightly packed together and can't hold water.

The other factor is permeability. Permeability is how connected the free spaces in a material are. This helps determine if the water can move or transfer through the ground or other material. For example, a cloth is highly permeable; the free spaces are tightly connected and so water is able to pass through the cloth via the network of connected free spaces. On the other hand, a plastic bag is not permeable. The free spaces are not well connected, and so water cannot pass through the plastic.

## Aquifer

Now, let's discuss aquifers. Groundwater doesn't stay in the ground forever - at some point it comes back to the surface or flows into the ocean. An aquifer is the location where groundwater comes back to the surface from underground. Many towns around the country use aquifers for water supply. There are many naturally occurring aquifers as well, in some instances, a lake can be fed solely by an aquifer.

## Issues with Groundwater

Groundwater is essential, but it can also be problematic. Let's look at two common issues regarding groundwater: contamination and subsidence.

To unlock this lesson you must be a Study.com Member.

### Register for a free trial

Are you a student or a teacher?
Back

Back

### Earning College Credit

Did you know… We have over 79 college courses that prepare you to earn credit by exam that is accepted by over 2,000 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

### Transferring credit to the school of your choice

Not sure what college you want to attend yet? Study.com has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it free for 5 days!

#### Explore our library of over 30,000 lessons

Click "next lesson" whenever you finish a lesson and quiz.
You now have full access to our lessons and courses. Watch the lesson now or keep exploring.
You're 25% of the way through this course! Keep going at this rate,and you'll be done before you know it.
1
The first step is always the hardest! Congrats on finishing your first lesson.
5
Way to go! If you watch at least 30 minutes of lessons each day you'll master your goals before you know it.
10
Congratulations on earning a badge for watching 10 videos but you've only scratched the surface. Keep it up!
20
You've just watched 20 videos and earned a badge for your accomplishment!
50
You've just earned a badge for watching 50 different lessons. Keep it up, you're making great progress!
100
You just watched your 100th video lesson. You have earned a badge for this achievement!
200
Congratulations! You just finished watching your 200th lesson and earned a badge!
300
Congratulations! You just finished watching your 300th lesson and earned a badge!
500
You are a superstar! You have earned the prestigious 500 video lessons watched badge.
1K
Incredible. You have just entered the exclusive club and earned the 1000 videos watched badge.
20
You have earned a badge for watching 20 minutes of lessons.
50
You have earned a badge for watching 50 minutes of lessons.
100
You have earned a badge for watching 100 minutes of lessons.
250
You have earned a badge for watching 250 minutes of lessons.
500
You have earned a badge for watching 500 minutes of lessons.
1K
You have earned a badge for watching 1000 minutes of lessons.
Support