How Wells & Aquifers Actually Work

Correcting the misconceptions that abound around water below the ground

It is undoubtedly unintuitive that water flows in the soil and rock below our feet. This video covers the basics of groundwater engineering, including how wells are built, how injection wells work, and how aquifers interact with surface water features.

Errata: Deep well jet pumps exist that can lift water greater than 100' using an ejector and two pipes.

Practical Engineering is a YouTube channel about infrastructure and the human-made world around us. It is hosted, written, and produced by Grady Hillhouse. We have new videos posted regularly, so please subscribe for updates. If you enjoyed the video, hit that ‘like’ button, give us a comment, or watch another of our videos!

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DISCLAIMER
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This is not engineering advice. Everything here is for informational and entertainment purposes only. Contact an engineer licensed to practice in your area if you need professional advice or services. All non-licensed clips used for fair use commentary, criticism, and educational purposes.

SPECIAL THANKS
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This video is sponsored by Nebula.
Stock video and imagery provided by Getty Images, Shutterstock, and Videoblocks.
Tonic and Energy by Elexive is licensed under a Creative Commons Attribution License
Producer/Writer/Host: Grady Hillhouse
Editor/Production Assistant: Wesley Crump
Script Editor: Ralph Crewe
Graphics: Standard Studios

[_Pyroon_]

This man has consistently made me more interested in dirt and concrete

[dj_laundry_list]

He is named Grady Hillhouse because he likes grades, hills, and houses. The ultimate civil engineer

[jacksonburke]

As a hydrologist and geotechnical engineer, I can't tell you how much I appreciate your videos. Even after my education and experience (in the field and office), your videos always seem to give me a better understanding of... well, just about any topic. Thank you!

[HanTheProphet]

You consistently have the coolest visual aids, but this was one that really helped me understand this better.

I was also thinking while watching this that this is such an efficient way to spread this information. A teacher may have to build and run this diagram every year, but you're educating millions for the amount of water used for a shower and some acrylic. Well done.

[Anonymous-rhhk]

In the Netherlands coastal regions they found that the dunes would hold a lot of clean water. They started pumping this water up around the 1870s, but ran into problems by the 1940s: salt from the sea would infiltrate the aquifer and make the water undrinkable. Now they pump fresh water into the dunes from rivers and pump it out on the other side. This allows for water storage and at the same time the sand in the aquifer cleans the water. This works so well that they don't have to add any chlorine and still have safe drinking water.

[thearth]

Something else to know: "Fossil" aquifers. There are many aquifers that are so deep and geologically isolated that they practically don't recharge at all. Once the water is removed it can take millennia to return. These aquifers are essentially a non-renewable resource (like oil) and unfortunately many places have become reliant on them, setting themselves up for catastrophic water shortages when the aquifers run dry.

[shwewpr]

I enjoyed your video on groundwater - these are concepts that are often difficult to grasp, and you have done a remarkable job of explaining them. I know from experience, because I was a professor of Hydrogeology (yes, there is such a thing) before I retired, teaching at the 3rd y level and up. What I love most about hydrogeology is that it draws from all sciences: chemistry (aqueous, organic, and even isotope), physics (Darcy's law in particular); statistics (when dealing with heterogeneous aquifers); Mathematics (as the universal language); numerical methods and computer programming. It can be a fairly simple applied science, as you have so well illustrated; but it can also be quite a bit more complicated for example in describing muti-fluid flow in heterogeneous aquifers (think for example of gasoline spills in layered aquifers).
One small addition I would like to make to your great presentation is that, in most practical applications, water movement is actually driven by a gradient of Hydraulic Potential in the direction of flow, which is made up of a pressure component and a gravitational component; not just pressure. If the aquifer is uniform and has no preferred direction of flow (or is "homogeneous and isotropic") the only time that flow is driven by a pressure gradient is in special conditions such as when flow is horizontal (no gravitational component), otherwise it is driven by the Hydraulic gradient (made up of both components). So, to properly and quantitatively describe flow in your (very nice) aquifer model you would need to use the Hydraulic Potential (often expressed in units of length of water or "Head"), particularly as you get nearer a pumping well.
Sorry for the rambling (gosh I love this stuff)!

[Zelmel]

As someone who is having long-term residential well issues, this video has been amazing at explaining just how these systems work in a way I hadn't previously understood properly.

[desmond-hawkins]

The use of dye tablets to show the flow of water was a great idea! This worked much better than I thought it would, it's striking how much they "draw" the path taken instead of just dissolving in the surrounding area.

[austinpatrick]

I treat well water for a living and honestly I figured out much of this intuitively during my time treating water and seeing how newly drilled wells affect existing wells and how depth of a well gives different water and countless other phenomena we run into. But this is the first time I've seen it explained so well and I definitely didn't know everything you said, and most of it was only assumptions based on experiences until you confirmed some things. I love geology and live and work in a place with VERY complex geology and it's awesome to have a job I enjoy that feeds off of that interest. Thanks for this video! I've sent it to the other guys I work with.

[PhilRable]

Your “garage models” are fantastic they make understanding the topic so much easier. You’re a great fabricator as well as an engineer.

[williamgeorge]

Wow. "#1 channel on the internet about dirt". The hubris of man truly knows no bounds.

[redlogicsquare]

"Even now, the rules that govern groundwater in many places are still WELL behind our collective knowledge of hydrogeology." nice! One of the many nerdy reasons why I love this channel. :D

[dt]

Greetings from a Hydrogeologist in Australia! Loved your model, if only all aquifers were that simple 😉

[Trixtah]

One of the most fascinating things I encountered as a kid was a stream near the top of some sandstone cliffs that literally disappeared into the ground - if it'd kept flowing above ground, it would have made a waterfall over the cliffs about 150m further on. It wasn't till months later I found 'another' stream bubbling up from the ground that flowed in the same direction as the clifftop one, but at least 300m from the base of the cliffs, descending towards the sea a kilometre or so away.
It was a pretty fascinating look at what seemed to me to be definitely part of the same waterway. The cliff also had small caves and voids in it for sure, although I never found a channel that matched the apparent full path of the stream - obviously, it may not have existed in one piece in the way I imagined when I was nine or ten.

[tannercotham]

As someone who drills water wells and installs complete systems, this was pretty fun to watch.

[fsmoura]

When I saw the title I was all pumped up to see this one. It did not let me down... drilled deep into the subject and presented it very well. ✔

[dbackscott]

Thank you for talking about this. I’m a geotech in Florida, but did some environmental work right after graduation in Arizona. I remember having to shut down numerous dry wells (shallow injection wells for storm water management) due to contamination issues. People thought those were the magical holes that made hazardous chemicals disappear. In reality, those were the “expressway” to the aquifer we used for drinking water.

To my knowledge, the Phoenix area is still dealing with plumes of groundwater contaminants that were dumped into the aquifer via dry wells or other injection wells 30 to 40 years ago.

[Torque]

Excellent video, one note from someone highly versed in wells and aquifers: contamination won’t generally occur as readily as your model would suggest in non-consolidated wells (if at all) as the general functionality of wells relies on the casing being a lower pressure space than the surrounding aquifer so water flows in and up to a static level (of course barring artesian wells). It’s like trying to shove a contaminant into an open spigot. The contaminate would have to be denser than water, highly soluble yet able to resist denaturing and at such a concentration as to not be diluted to a point of “who cares”. The well would also have be relatively inactive (avg water use per person is 100gal/day) in order for the contaminant to truly propagate into the aquifer. It would have to be a perfect storm of conditions or gross negligence to result in any significant contamination to an aquifer.

However, that said, your contamination model would be more relevant for consolidated wells that feed from above and some bucket wells.

Other than, spot on, fantastic modeling and a very educational video!

[ykhus]

Petroleum engineer here. Excellent video, and I loved the demonstration. It's reassuring to see Darcy's law at work with streamlines forming along the pressure gradient. It irks me that civil engineers call permeability, hydraulic conductivity though, but to each their own I guess. 👍