Installing a French Drain




About: Building things to pass the time and sharing the good ones with others.

If you live in a part of the world that receives a fair bit of rain, then you are probably pretty mindful of water and how it effects your property.

I live in the beautiful state of Maryland. My home is built on clay soils. And when it rains you can bet that not all of that water quickly percolates through and into the earth.  

The purpose of this "how to" is to serve as a visual reference for constructing a hidden drainage ditch in your yard if you have limited standing water issues on your property.

A common term for this kind of approach is a "French Drain

Oh disclaimer time: Before you dig ANYWHERE, make sure you contact your local utilities people. It can't be stressed enough that the danger of damaging a line in your yard is a real possibility whenever you dig (It also becomes your responsibility if you knock out your neighborhoods power, so call first then dig.) Also, do not do this procedure very close to your foundation. Check with a landscaping company if you don't want to get your hands dirty. A little bit of research and you can feel pretty confident to do this one on your own. 

Alright? Let's go! 

Step 1: Materials and Methods

Required Equipment
A muddy poorly drained yard. 
A cast iron constitution if you're digging this by hand. 
A long length of string/rope
A line level
A couple of round point shovels 
Iron tooth rake
Wheel barrow
Landscaping Cloth
Utility Knife
Water source
Grass Seed
Stones of various sizes, depending on your project you will need quite a lot of pea gravel, stones, rocks, etc. Usually come in 0.5 cu/ft bags. You can acquire a lot of stone from your local garden center. Just do your math. Length x width x Depth of your trench will be your total volume. Buy more rock than that and you'll be good to go.  

Step 2: Dig, Lay Cloth, Fill Stones.

Step 1 Acquire a helper. No minion this time. You need someone with whom you may confer. You'll be determining start and end points, depths, and even a slope on this job. 

I took the side of the yard to right of the tree (see image 1) as the start of the drain. From there I dug an approximate 1--2% slope across the face of my patio, around the corner and to the edge of the fence. (This by no means got me to the street! So far! I could have, but I decided to drop a small stone well under my stepping stones. You basically dig 2-3 feet down and fill that hole with stones. This will allow the water to percolate down through the soil at this point very quickly and serves as the outlet to the drain.) 
Use your lines, line level, and helper to establish your drain's direction and slope. Remember, however many feet your trench is going, is how much deeper the end of your trench will be. 

Step 2
Take a step back and do the math. Be sure that you're not going to be 4 feet underground. If that is unavoidable you may need to do a more extensive project than this guide provides. (Check this one out

The trench should be about 6 inches in width and sloping to 2 ft in depth (depending on your distance, remember we're doing 1-2% slope, so for every 10 feet you'll drop ~2.5 inches. (Go here if you want more info

Once it is dug, Get your water out and your bucket or hose. Test your drain. Ensure that the water is flowing in the right direction and at the appropriate speed. open up any stuck areas. Clear the trench of excess sticks and roots (there will be LOTS). Once it's running the way you like, you're ready for cloth and stones.  

Step 3
Landscaping cloth should be cut into small manageable lengths and widths. It should be much wider than your trench because you'll need to fold it over to cover the stones with them later. You need to remember that the cloths should be overlapped in such a way that the running water will not run under the cloths.

Essential: Lap your cloths so that they look like house shingles in the direction of water flow, think of how a fish scales look. 

If the water direction is -----------------> 
Got it? 

At this point you could also include a small 2-3 inch PVC pipe with holes drilled into it along its' length. The stones provide the channel and the support for the drain, but the inclusion of a pipe here will improve the efficiency of your drain quite a lot.  I did not use a drain pipe, it was more than I needed for this job. See the previously linked "how tos" if you'd like more information. 

Step 4
Once you've laid out all your cloths, start filling with stones. Put the big ones in first and then cover the bigger ones with the pea gravel.  Take your time. Make sure you've got even coverage. 

Not optional: 
Be nice to your helper on this one. Rocks are heavy. 

Step 3: Cover, Soil, Seed.

Almost done! 

Now, you've gotten your stones down to the end. You've filled in your small stone well. You're ready to cover the stones with the remainder of your landscaping cloth and can put the topsoil down. 

Topsoil? How will the water get to our drain? Because topsoil will allow the water to percolate down to your drain much better than the previous soil that was there. Also, by putting down topsoil, we can plant grass. Plants are excellent at keeping the soil aggregates from agglomerating. (Alternatively, if you want to go hog wild here,  you can put in a gravel walk way which will be an added boon to your drain and will hide all this work. If that's your plan, stay tuned, I will be posting of of those really soon.) If not, continue: 

Cover your drain with topsoil and seed the heck out of it. 

Water your new grass every day or so, depending on the weather. Once the grass starts coming in, your drain will perform even better. Check my before and after pictures. It's a fun project and it requires a bit of strength and thought. 

Thanks for checking it out. Good luck on your project ! 



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    36 Discussions


    3 years ago on Introduction

    I am currently putting in a french drain in my basement to solve the issue of water coming in 2 and 3 courses up the block wall. I have almost completed digging all of the trench system. In one area, the sewer line crosses the trench and related to maintaining the slope, there is no way over or around this pipe. My thought is to terminate the pipe and restart the pipe on each side of the pipe. Just curious if anyone knows of the proper way to do this? Do I just fill around that area with gravel and assume that if the water level climbs high enough, it will flow into the drainage side of the terminated pipe? Do I have to worry about erosion that may happen under the concrete floor? As this may assist, I am using drainage PVC pipe and not the flexible drainage pipe. I also plan to wrap the loose gravel and the drainage pipe in landscape cloth. Any assistance would be appreciated!

    3 replies

    Reply 3 years ago on Introduction

    This is one where you may just want to bite the bullet and have a couple contractors come out and give you some onsite advice. Without being able to physically see the issue, it is very difficult to provide you a good answer.

    Also, if you have water coming into your basement, you may want to look at some exterior solutions such as sloping your land away from the foundation, fixing your gutters which may be blocked, and applying block bond material to the areas where you're seeing ingress of water.

    airborne pickle

    5 years ago

    Thanks, I sharing this. I had a similar problem but it was two fold. I had to manage new trench for storm water and a French drain across a stretch of that pipe. Hard to picture but I used an unperforated flexible pipe(Novo coil) for the storm water section, and where the French drain was, I punched dozens of holes and wrapped that section as you described. That French drain portion now catches water from our unsealed driveway and feeds it into the new storm water.

    1 reply

    after the writing of this instructable, we had the property manager of the place next door help to tie into our drain line. We pulled the downspouts of the neighbor's roof into the existing drain and helped move the water out into the drain near the street.


    5 years ago on Step 3

    Enjoyed your sense of humor in your instructions. Nice work!

    1 reply

    7 years ago on Step 3

    This is an excellent project and can save an otherwise useless yard.
    when i did it, i had a shed in the way of the view so we used a laser surveyors transit. we shot a line from each end of the drain to the back wall, drove in a nail where the dot landed. Between the nails there was a 4in drop. in the trench, i laid the black perforated plastic drainpipe covered with landscape cloth. it's lasted for years.

    7 replies

    having that transit is an awesome bonus. I'm glad your project worked so well. We were a bit skeptical when we started, but the results have been very acceptable from our end. No unwanted backyard lakes!


    Reply 7 years ago on Introduction

    All the contents you mentioned in post is too good and can be very useful. I will keep it in mind, thanks for sharing the information keep updating, looking forward for more posts. Thanks.

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    Just though of another point. It's already mentioned in the text, but it really needs to be in BIG GLOWING NEON RED letters - call before you dig!

    There are areas where the lines are supposed to go but on our front lawn, when the guy tried to scan it, it looked like the installers had a very long cable and didn't want to cut it and add new ends. They just tossed the extra cable out of their way. There were loops of cable all over(under!) the lawn.They finally gave up, cut it and put in a new line.

    Is that a rain barrel in the first photo by the shed?

    p.s. I agree with your use of the french drain in your situation, and I am grateful for your post because my backyard is essentially in the same situation as yours.

    3 replies

    Reply 7 years ago on Introduction

    The information provided here regarding the installation of french drain seems to be very useful for us.  This will really help in saving rain water as well as soil. Thanks a lot for this wonderful presentation.

    Clogged drain

    that rain barrel is from my other instructable. Easy to assemble. I'm a big fan of capturing the water I need and then handling the water I don't. Make sure you have a helper. It's a big job. You might be able to mitigate the problem by simply improving the soil, but that didn't work for me. I've got clay so I needed this solution. Good luck don't_unplug_me.