How French Drains Work

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You don't just explain the Science but 'Why it matters'. That's philosophy in my book.

One of my favorite fields of study is Engineering Philosophy. Questions like "to what degree is the engineer responsible for protecting idiots from themselves?" Based on that criteria, I would absolutely call you a philosopher, Grady. You have helped shape my perspective on engineering ethics, and I teach high school engineering, so your philosophies and opinions (no matter how mild) are permeating multiple generations of engineers. Keep up the good work!

Redirect water for me like one of your French drains

The hardest job I ever did was digging a French drain around my house built in 1780. The roots the roots!!!

As an environmental engineer, this is one of my favorite channels. I deal entirely with groundwater but never in the context of how it interacts with and affects structures. Thank you for your amazing content, Grady!

So during a piece of road construction I was inspecting a few summers ago in northern Michigan, we suddenly tapped into a spring that we didn't know was there late in the afternoon and needed to be ready traffic the next day for paving. I was pretty inexperienced at the time and had no idea what to do but one of the construction guys on the crew suggested using a French drain. I knew two things, water flowing underneath the road would ruin it and the guy talking about the drain knew more than I did. We were there until 4am adding stone and blanket. Let my boss know the next day and he was happy with the French drain

"It made a heck of a mess, pardon my French drain" is one of the all time great Grady jokes 😂

I used to install French drains. Common practice was to drill the holes in two lines at 90 degrees from each other, and orient them down at 45 degrees off center on both sides. This left a channel in the center for water to flow

I love the fact Brady complained that TV is all just reality TV shows and rhen proceeded to promote the Getaway which while a great show is still yet another reality show.

Literally calling companies two days ago to get quotes for a french drain. This video gives me so much info on what I need to know. Thanks for posting.

"Once you know the base soil's grain size distribution, there are a number of engineering methods to find a material that will both allow water to flow while still holding the soil back." Would you be willing to cover this in more detail, or at least provide some references to this sort of thing? I want to know more!

When I was younger, I watched my dad build a French drain and he told me the holes had to go on the bottom. The entire thing completely baffled me and it was a burning question for years about how it worked. Thanks for finally answering the question I had when I was younger, but forgot about 😅

You are, indeed, a philosopher. The pursuit of knowledge about the natural world and how it works is exactly what the original philosophers were.

You have to admire the simplicity of the humble French drain. I'm from Connecticut and we have tons of these all over the place. Truly, you cannot understate the amount of rock in the soil here. So its no wonder why we have so many of them. It makes it pretty easy to see how well they work as long as you know what to look for.

We could use a lot more water management practical, personal advice. I've had to learn about slopes, swales, and drains for runoff. Next I have to learn about septic systems, percolation tests, and how regulations among restrict what you can do--or what you have to do. Friend of mine is struggling with erosion from tides, and I don't fully understand if what the neighbors are doing (laying down large walls of boulders, stacked 6x6s, or concrete) is the end-all-be-all or if friend's planting of ground cover could be good enough, or if there's something more smart they could do by analyzing the specific fluid dynamics of that waterfront. A wise old guy told me to avoid french drains with ribbing, for example--they clog easily, apparently. He said to stick with smooth piping.

I put french drains behind a cement block retaining wall I rebuilt 15 years ago. Dig out behind wall-put geo cloth in with lots of excess on both sides-lay in perforated drain pipe with a cap on one end-back fill with gravel-fold geo cloth over top if gravel with a big overlap-backfill with soil. It hasn't budged in 15 years.

I absolutely adore the way you convey information in your videos. From engineering handbooks to failure analysis, your use of references and practical demonstrations always leave me with a feeling of greater understanding. I'm not even a civil engineer (electrical over here), but the content you deliver is always interesting and widely accessible.

6:51 That bug must be having the weirdest day.

I am a Stormwater Management/Sediment Erosion Control Inspector for the state of MD, and we don't allow French drains for the exact reason Grady stated. No matter how much you try to regulate sand/gravel size, any smaller sediment particles above, and in contact with, larger stones, will enter and clog the spaces between the gravel. We typically use very similar devices like Bio-retentions/Micro-bios in residential areas between houses. There is a whole world of mildly interesting devices and structures used just for moving around the water that comes from the sky, and the ultimate goal is to have the water end up in the exact same place it was before it was developed. Its also always changing, and things we were doing 5-10years ago is already considered out of date, but awesome video as always. Absolutely nailed all the nuance in this field! Keep up the great work!