French drains are a very efficient way to their solve water problems… which can be a home owners absolute worst enemy. I’ve struggled with my fair share of water problems so I can understand the frustration that you may be feeling right now trying to solve this problem.
What is a french drain and how can it help?
A french drain is an underground trench or pipe designed to collect water and redirect it to a different location of your property. French drains can resolve pooling water or water runoff issues that have the potential to damage your property.
Some reasons you may need to install a french drain are:
- If water is pooling near your foundation.
- if water is not draining from a hard surface, such as your driveway or a patio.
- if water runoff from a slope in your property is creating a river in your yard washing out all of your landscaping.
You may also be wondering what a french drain looks like.
In most cases, you won’t see a french drain, because the trench is underground and can easily be hidden using sod or even gravel. Sometimes, a french drain is disguised as a dry creek bed, making it a functional and beautiful focal point in the landscape.
If you want to install a french drain at home, this is a DIY project that most home owners can handle with a little sweat equity. Here are the steps that I’ll cover in detail:
- Determine where the drain will begin and end
- Create a mouth to collect water at the beginning of the drain
- Dig the trench
- Line the trench with landscape fabric and secure in place
- Add a drain pipe to the bottom of the trench (optional)
- Test the drain
- Fill the trench with stone
- Cover the stone with landscape fabric to hide the drain (optional)
- Install landscape edging along the sides of the trench (optional)
French drain distance from house
You may be wondering how far away from the house your french drain needs to be. In a perfect world, you should have the drain running at least a foot from your foundation… but it’s not completely necessary if you are working with a really tight space.
I have seen landscapers install french drains right up against the house, flush with the foundation! However, if you want to run your drain that close to your home, you should prepare the foundation of your house first. You can do this by brushing tar onto the foundation to seal it. This creates a barrier between the running water and the porous concrete foundation so that you don’t create even more water problems for yourself.
So, it doesn’t make much difference if it is next to the foundation or a foot or two away. Although, if I had the option, I would not put the french drain right up against the house… just to be safe.
Also keep in mind that if you put the french drain more than two feet from the foundation, there may be a water table gradient that rises as you get closer to the foundation. So, you’ll want to stay within that 1-2′ distance to properly displace water pooling near your foundation.
French drain slope
It’s obvious that the end of your french drain needs to be lower than where the drain begins… but what is the appropriate slope of a french drain? As a rule of thumb, the french drain should slope downward at least 1″ for every 8′ of length.
How deep should the french drain be?
Far more important than the drain’s distance to the foundation is that the bottom of your drain be at least six inches lower than the maximum groundwater water level you are willing to tolerate. If possible, the bottom of the drain should be about 12″ below the base elevation of your home.
But, this isn’t a hard and fast rule and the depth criteria can be adjust a bit to fit your specific situation. It’s just a rule of thumb guideline to follow if possible.
The best pipe material for a french drain
One of the most common pipe materials used to create a French drain is 4″ plastic pipe because of its durability. Pipes for french drains also include holes that allow the water to seep into the drain. The holes should be positioned facing upward. Hopefully this is obvious but it’s worth mentioning!
Here are the two most common types of plastic used for french drains.
- corrugated pipe – lightweight and flexible plastic.
- PVC pipe – stronger and more rigid plastic, while still being lightweight.
Just be aware that a french drain does NOT have to include a pipe to be effective. You can create a trench using just landscape fabric and fill rock if you prefer.
Using landscape fabric for a pipeless french drain
You can also make a french drain that doesn’t contain a pipe at all! To do this, you’d simply dig a trench, line the trench with landscaping fabric and fill with gravel/stone. Some people refer to this as a pipeless french drain and it’s just as effective as a french drain with a pipe to carry the water.
There are two ways that home owners accomplish this type of french drain. In both methods, a trench is dug out to about 16-18″ depth, then landscape fabric is laid at the bottom of the trench. Then you fill the trench with gravel. In one variation, the french drain will be left open so you can see all of the stones. In the other case, the drain will be covered by topsoil and sod or grass (more on this later).
Regrading: an alternative to installing a french drain
If you have water that’s pooling up against your house, you may be able to regrade the slope of your lawn in order to divert the water away from your home. This is a great solution that you can try if you have the right conditions!
But, if you decide the a french drain is the way to go, keep reading for step by step instructions to get this done without hiring a pro.
Materials you’ll need for french drain installation
- Shovel (to dig your ditch) – I like the Fiskars D-Handle square garden Spade, that you can buy on Amazon
- Commercial grade landscaping fabric (6′ width) – I like this geotextile fabric you can buy on Amazon
- Landscape staples to pin the tarp to the side of the trenches (buy on Amazon)
- Lime rock to backfill the drain
- Landscape edging material – to make a neat and clean edge along the sides of the french drain. This isn’t required but if you want to do that I like this plastic edging you can buy on Amazon.
DIY french drain (step by step)
Determine where the drain will begin and end
The first thing you need to consider when installing a french drain is where the water is pooling and where you will redirect the water. You’ll need to make sure that the water moves downhill or this will not work. So when you choose a location on your property to “end” the drain, this should be on lower land than the place where you started the drain. The drain should go downhill.
Create a mouth to collect water at the beginning of the drain
At the beginning of the drain, where the water is currently pooling, you’ll need to create a mouth, or opening, to collect the water. It’s a good idea to make this opening a bit wider than the rest of your drain will be so that it’s able to collect more water.
You can also install a catch basin or a drain box at the mouth of your french drain to aid in collecting water. But, with the v-notch style trench we’ll be digging this isn’t 100% necessary to do. If you position the drain correctly, water can flow into it for the entire length of the drain. The water does not necessarily need to enter the drain at the “mouth” or beginning.
Dig the trench
Most people would complete this project by digging a BIG ditch by hand or with a trencher. But there’s actually a more efficient (and less laborious) way to create a french drain in your yard. You can make an effective french drain by digging out the ditch in a triangular (or pointed) shape.
To create a triangular trench, or a v-notch, dig down at a 45 degree angle towards the center of the drain. Then go along the other side of the drain and do the same thing. The result will give you an upside down triangle shape like in the photo below.
With this method, the “tip” of the triangle is at the deepest point of the drain, which is about 16-18″. This is pretty easy to handle using a square shaped shovel or a trench shovel.
Once you dig the trench, clean out any of the loose soil and debris to prepare it for the landscape filter cloth.
Cover the trench with landscape fabric
Spread the landscape filter fabric across the trench and secure it with the landscape staples on one side. Pull the fabric down into the bottom of the “v”… you can add another staple at the bottom to hold it in place. Then bring the fabric up the other side and, again, staple it in place. You are just wrapping the drain with the fabric.
If you plan to completely cover the drain with soil and grass, make sure that you’ve started at the edge of the fabric and have a decent width left of the landscape fabric so you can fold it back over top of the gravel. Kind of like a pita or taco would hold the meat (or in this case, the rocks).
Add a drain pipe to the bottom of the trench (optional)
Once the fabric is secured, you can add your drain pipe into the bottom of the trench. This is optional — a french drain does NOT need to have a pipe in order to be effective.
Test out your french drain
You can use your garden hose to run water into your new french drain to make sure that it will flow properly. I would recommend testing the drain right after you install the landscape fabric just to be sure that you have the slope of the drain correct.
Fill the trench with stone
Once the fabric is secured into the trench you’ll just fill the entire trench up with gravel. If you plan to create an invisible french drain, be sure that you don’t fill the drain completely to the top with stone. You’ll need some extra room for topsoil and sod to be placed on top. If you plan to leave the stone exposed, you can fill the stone up to the top.
Cover stone to hide the drain (optional)
You can cover the stone that you’ve just laid in order to make your french drain invisible. But, this is an optional step. You can also leave the stone exposed to give your french drain a “dry creek bed” look that can add interest to your landscape.
Quick Tip: For more “aesthetic” landscape ideas, check out my post about Landscape Layering.
Create an invisible french drain
If you want to completely cover the french drain with soil and grass so that you can’t even see where it is on your property, I would recommend using 6′ width landscape fabric. With this width, you can line the bottom of the trench, pin it down, fill the drain with gravel, then fold over the excess fabric to cover your stone. This way you only need to deal with one connected piece of landscaping fabric rather than sandwiching the stone between two separate pieces.
Once the fabric is laid on top of the gravel, you can cover the fabric with a layer of top soil and plant grass. Or if you’d prefer to use sod, cover the fabric with a very thin layer of topsoil that’s recessed into the drain. Then cover the topsoil with the sod, making sure that the sod is level with the rest of your lawn.
Create a dry creek bed style french drain
Some people prefer to not cover the french drain with soil and grass. So this is also an option. You can dig the trench and line it with the landscaping fabric. Then, fill the trench with gravel and just leave this exposed in your yard as a decorative “dry creek bed.”
If you go with this method, you wouldn’t need the 6′ width landscape fabric because you won’t be “doubling” the fabric over top of the gravel. So, you can probably save a little money getting a 3′ or 4′ width fabric instead.
Then, you can use that extra money to purchase some nicer stone to use on top of your french drain to make the dry creek bed look really natural.
Install edging along the sides of the trench (optional)
This is an optional step, but adding some landscape edging along your french drain will make things look nice and tidy. I would recommend this step if you are planning to leave your drain open in the dry creek bed style. That’s because the edging will prevent your grass from inching into the drain area.
If you’re planning to cover the drain completely to make it invisible, there’s no reason why you would need edging.
V-Notch French Drain Video Tutorial
Most of the images used in this post are screenshots from this really informative video. I’d really recommend you watch this before you get started on your french drain installation.
As you can see, installing a french drain is not as intimidating as you may have thought. If you follow these steps, you can complete this project yourself… although it does help to have some friends to help you with the project.
If you are looking for another option to relocate water that’s pooling near you home, you should check out my popular post that will show you how to regrade the slope of your lawn.
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