7 French Drain Mistakes Most People Make

Are you experiencing drainage problems in your backyard and you’re unsure of how to fix them? French drains can be a simple solution to help you remove your excess water and collect rain to move it to a lower area where it won’t cause damage. You may want to give these a thought if you need regular water flow to prevent flooding and damage to the foundation of your home. 

When installing a French drain, you’ll want to avoid using the wrong drainage rocks, having the incorrect exit point, and forgetting your drainage fabric. These mistakes are crucial to avoid in preventing pooling water, damage to your foundation, efficient water flow, and ensures your French drain will last for years.

Mistakes when installing French drains often occur because the drain runs underground to collect and carry rainwater away from your home. Fortunately, these mistakes can be avoided with a careful and thought-out installation process. We’re going to go over some of the common French drain mistakes and how you can avoid them.

Common French Drain Mistakes

If you’re considering a French drain for your home, you should know that there are some common mistakes homeowners make when using them. Even though common mistakes are made, there are ways you can avoid them to prevent any unneeded stress and from spending more money. The last thing you need is a failed drainage system with unwanted water in your backyard.

A few common mistakes that you might make as a homeowner are that you use the wrong type of drain rocks, you don’t have enough positive slope for the drain, or you’re skipping drain pipes. Below, we’ve put together a well-detailed list of eight common French drain mistakes made by homeowners and how you can avoid them.

1. Using the Wrong Drain Rocks

When installing a French drain, you want to make sure you’re using the correct type of drain rocks. To have proper drainage, you must use the correct drain rock such as a clean, natural rock. This type of rock will encourage good water flow and will prevent your drainage system from clogging.

To use the best drainage rock, you’ll want to use a rock that is about 1 ½ inches, preferably a washed rock. You’ll want to avoid using small-sized rocks as this may minimize your water flow. You’ll also want to avoid any crushed rocks that may clog your drainage system and prevent water from reaching its exit point. 

2. Wrong French Drain Exit Point

For you to get the best function out of your French drain, you must have the best exit point in your property. The goal you want to achieve is to ensure that water will be moved away from the foundation of your home.

For the best drainage, you should ensure that your French drain is placed on a grassy slope that will receive plenty of sunshine. You’ll want to make sure the drain is placed near the area where you have the most problems and that your excess water can be emptied onto the street. The excess water will drain out into the public sewage system.

To save money, you should ensure that your French drain is installed around any utilities to avoid damages, which would be an additional, but very expensive cost.

3. Getting the Wrong Type of Landscape Fabric

One of the key parts of installing a French drain system is having landscape fabric. If this is your very first French drain installation, it might be difficult knowing where to begin when it comes to fabric. Using the wrong type of fabric will have you redoing your drain pipe.

The best type of landscape fabric you’ll want to use for your French drain is FLARMOR Premium Landscape Fabric. This fabric is at the top of the list because it allows for water to pass through, is easy to install, and does not break down fast. Not only will this fabric be easy for you to install, but it will also be affordable on your budget and stop any weed growth you might have around your home.

4. Missing Drainage Fabric in Trench

When installing your French drain, you mustn’t forget to line your trench. It’s important to line your trench because not only does it add security and promote structure, but it also helps in preventing erosion. This is very important if the water is being transported and not stored.

As time passes, you might notice that water will begin to weigh down the trench, which will affect the way the water flows. Making sure you install a trench liner will help minimize the chance of you dealing with erosion. When installing your liking, you’ll want to use a George tile drainage fabric. 

This will be the best type of fabric to use for your French drain because it’s high quality and can last for years without any problems. An important thing you’ll want to remember is to not use wrapped perforated pipe because it can clog when paired with soil.

5. Placing Excavated Soil Back into Trench

When installing your French drain, you’ll want to avoid placing excavated soil back into the trench. This is an important step that will prevent your trench from settling, shifting, and eroding. For you to do this correctly, you’ll need to know the steps to follow to ensure the best results. 

The first step you’ll want to complete is to choose your method. Four methods you’ll have to choose from are filling, compacting, dumping, or jetting. Next, you’ll want to choose the type of soil to add to the trench. You’ll be able to choose from uncompacted soil, compacted soil, compacted stone, or lean concrete.

After you have chosen your type, you’ll want to gather your equipment to ensure the best results. The four types of compaction equipment are rammers, plate compactors, trench rollers, or compactors. Lastly, you’ll want to fill your trench.

The best method we recommend on choosing is the compaction method. This will give long-lasting results for your French drain and ensure it remains stable.

6. Not Enough Positive Slope of the Drain

If you aren’t careful of adding enough positive slope to your French drain, this could add potential problems to your drainage system. To ensure the water is properly draining, you’ll want to take your time to achieve the right angle of your pipe. There are 4 different slope scenarios you’ll want to keep in mind.

If your pipe is flat, this requires more energy for the water to navigate through the drain. If this occurs, you’ll have a zero-slope system. If you begin to notice water pooling and an increase in water by the drainage line, this is considered a low spot.

Another common scenario is the negative slope. This can occur if water can’t run through your pipe. If your goal is to drain water away from your home, a negative slope is not ideal since it has the potential to damage your foundation.

Lastly, you have a good slope scenario. This scenario will allow the water to drain away from your home and ensure it navigates along the drain lines.

7. Skipping Drain Pipes

Another common mistake you’ll want to avoid making is skipping using a drain pipe. If you skip using a drain pipe, heavy water will not be able to flow through the pipe, thus creating a problem of idle water. The main reason you want to use a drain pipe is to make sure that the water flows exactly where it should.

When choosing your drain pipe, you’ll want to pick one that is between 4-6 inches. This will ensure that heavy water can properly flow through the pipe and move the water away from your home. Inserting the wrong drain pipe may also go against zoning regulations for your area. 

8. Forgetting Zoning Regulations

When installing your French drain, it’s important to be aware of your local zoning laws, building codes, and any other community rules you must follow. The permits needed will vary from area to area. Before you begin installing your drain, you should call your local agricultural official to find out the codes for your neighborhood.

If your French drain requires a diverting stream, you’ll most likely need a permit. If your French drain doesn’t change the water runoff, then you’ll most likely not need a permit. Keep in mind that installing a French drain that is against your neighborhood’s codes can cost you thousands of dollars, so it’s important to avoid as many mistakes as possible. 

How Can I Avoid Any French Drain Mistakes?

As a property owner, you know when water doesn’t easily drain away from your home that this is a recipe for disaster. Having all of that extra water around your home only means that your foundation will take on damage.

To protect the foundation of your home, you’ll want to avoid mistakes when installing your French drain. Now that you know the common mistakes you can make, here are some ways you can avoid them. 

1. Know Your Local Zoning Regulations

Before you begin to install your French drain, you must know about the zoning laws in your area. These laws will regulate aspects of your property. For example, the zoning laws will tell you where exactly you can install your drain and how far on your property you are allowed to install it.

Zoning laws will help stabilize your property value and your neighborhood compatibility. It will also help to keep your neighborhood convenient and safer. To check the zoning laws in your area, you’ll check your city and council ordinances, check conditions and restrictions, and seek a variance.

2. Pay Attention to the Direction of Water Flow

Another mistake you can avoid making when installing your French drain is making sure you’re paying attention to the direction of water flow. You’ll want to pay attention to the direction of water flow because if water starts to build up and sit around your home, this could cause your foundation to become unstable.

To prevent any flooding to your home, you’ll want to make sure that the water flows in the trench, goes down through the gravel, and into your pipe. This will ensure that the water will be diverted away from your home. The gravel will also prevent any excess debris from passing through.

3. Figure Out the Correct Slope

Nothing will ruin your day more than installing a French drain that won’t dry. This is why it’s important to figure out the proper slope you’ll need. The first step you’ll want to take is to measure and plan, which is essential to figuring out the slope you’ll need. 

For you to have an accurate calculation, you’ll need to make sure you know the correct length of your pipe will travel. To do this, you should plan your drain route and use the shortest distance. To figure out your slope, you’ll want to multiply the number of feet your pipe is by the inches you plan to slope. 

When multiplying these distances, this will give you the difference in height starting from the beginning to the end of the pipe. If you’re having trouble calculating the slope, you can always call your local plumber to assist you.

4. Place Lining in Your Trench

One key step you want to make sure you don’t forget is to place lining in your trench. For a long-lasting French drain, you’ll want to install a heavy commercial filter fabric. This type of fabric will allow minerals to pass through so they won’t build up on your fabric.

It’s crucial to line your trench because you’ll want to avoid any dirt or other debris from coming into contact with your rock. Not having a lining for your trench could prevent water from flowing freely.

5. Use the Right Type of Gravel

When you begin to install your French drain, you’ll want to make sure that you are using the right type of gravel. The best type of gravel you’ll want to use is hard rocks, like granite or river gravel. This type of gravel won’t erode and cause you problems down the road.

You’ll want to make sure you avoid using smaller gravel, as this would not allow water to flow freely. Whichever type of gravel you settle on, make sure you choose a washed rock so particles don’t hinder your water flow.

6. Do Not Skip the Drainpipe

Almost every type of big project that involves water requires a drainpipe. The purpose of a drain pipe is to transfer water from one area to the other. If you skip adding a drain pipe during installation, you could end up dealing with water buildup, flooding, structural damage, erosion, and more. The last thing you’ll want to deal with is shelling out more money, especially if you’re already on a budget.

We know picking out the proper drain pipe may be time-consuming, but skipping this key step in the installation process would be more of a headache. When choosing a drain pipe, we recommend opting for a metal drain to avoid any rust or erosion.

7. Correctly Direct the Pipe Holes

Have you been struggling to find out which way to direct the pipe holes during installation? You’ll want to direct your pipe holes downwards because the water flows from the bottom of the trench, up towards the pipe. Many people think that having holes at the top would mean that the water would fall, but this is simply false.

This is a key mistake that many homeowners make so make sure you go over this step thoroughly. Your pipe will overall have better performance and transport the water much faster if you direct the holes down. A properly installed French drain is important for the sake of your home and neighborhood. 

Why Is A Properly Installed French Drain Important? 

If you’ve been dealing with standing water around your home, then you’re aware that properly installing a French drain is crucial for top performance. When you bought your home, you probably thought that the contractors kept in mind water drainage, but this isn’t always the case.

Properly installing a French drain is important so you won’t have to deal with any damage to your foundation, which could end up costing you thousands of dollars.

A proper installation can help you avoid mistakes by simply following the steps one by one. These key steps will help prevent standing water, soil erosion, and protect your foundation from unwanted moisture.


In conclusion, avoiding these common French drain mistakes not only will save you additional work but will help you save money in your pocket. By avoiding these mistakes, you can ensure that your drain will provide long-lasting results and prevent needing to reinstall your French drain.

Tip: if you’re struggling to complete this project on your own, you should contact a landscaping or plumbing expert to assist you with installation.

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