Filter Fabric for French Drain Systems: Choosing the Right One for Clog Prevention

By thewriteDuffy •  Updated: 05/02/23 •  11 min read

While installing a French drain can be an effective way to move water away from your home, it’s essential to use filter fabric, or geotextile fabric, during its installation to ensure the longevity and effectiveness of the whole system.

Filter fabric acts as a barrier that prevents sediment and debris from entering the drainage system. Without geotextile filter fabric, these materials can accumulate within the perforated pipe causing blockages or clogging which can lead to backups and flooding.

Using filter fabric for your French drain not only increases its lifespan but also provides efficient drainage by filtering out any unwanted materials that can potentially cause damage to your property. In this article, we will explore what exactly filter fabric for a French drain entails and how it can be installed properly.

The Purpose of a French Drain

A French drain is a type of drainage system that helps move water away from an area. It is typically constructed by digging a trench, inserting a perforated pipe, and filling the trench with gravel to help water flow freely through the system. The purpose of a French drain is to prevent water from collecting in unwanted areas, such as basements, crawl spaces, and yards.

What Is Filter Fabric for French Drain?

As the name suggests, filter fabric is a type of material that filters out unwanted debris and sediment from entering the French drain system. It is a permeable membrane that allows water to pass through while trapping silt, sand, and other particles.

The filter fabric acts as a barrier between the soil surrounding the French drain and the drainage pipe itself. Water enters through the perforated pipe and flows into the gravel bed surrounding it.

The filter fabric sits on top of this gravel bed, preventing soil particles from entering and clogging up the system. Without proper filtration provided by high-quality filter fabrics, dirt and debris will eventually settle in your drainage pipes causing blockages and making your drainage system ineffective at best.

Types of Geotextile Filter Fabrics Available in The Market

There are two major types of geotextile fabrics available – woven and non-woven.

Woven Geotextile Landscape Fabrics

Woven fabrics are typically made from linen, polypropylene, or polyester fibers. These fabrics are typically impermeable, and water drainage through the material is minimal.

A woven geotextile is made up of polypropylene layers that are cut and pressed and woven into sheets of high tensile strength. The result is a premium filter that’s resistant to clogging from dirt, sand, or other debris.

Woven geotextile fabric has high durability (pull strength) and warp resistance making it a great material for supporting heavy loads, tolerating road ruts, extending pavement life, and acting as an effective sediment barrier.  

Due to its low permeability, this fabric is not ideal for drainage applications.

Woven geotextiles are instead an excellent choice for projects requiring water to flow over a subsurface. 

Common Woven Fabric Applications:

Non-Woven Geotextile Landscape Fabrics

Non-woven fabrics are created using synthetic fibers that are mechanically bonded together to form a sheet-like material.

Needle-punched and poly-spun non-woven geotextile fabrics are both sturdy and versatile. This fabric is most commonly used to support drainage, filtration, and ground stabilization in landscapes.

These fabrics feel like felt when touched and are available in lightweight, medium-weight, and heavy-weight options.

Common Non-Woven Fabric Applications

Which Geotextile Fabric Should You Choose for French Drain Systems?

Selecting the proper filter fabric for your French drain is crucial in ensuring the system’s effectiveness.

It’s very important to note that non-woven geotextile landscape fabrics, which are commonly used for weed control, is not suitable for use in a French drain.

Instead, you should opt for a non-woven geotextile fabric specifically designed for drainage applications. This type of fabric allows water to pass through freely, without any pooling or puddling, while preventing fine soil particles from infiltrating and clogging the system, thus maintaining its functionality and reducing the need for frequent maintenance.

To gain a better understanding of why how well geotextile fabric that’s meant for drainage systems works, check out this YouTube shorts video by French Drain Man, showing it in action:

As I mentioned above non-woven geotextile fabric comes in several weights, 4 oz fabric is most commonly used for French drains as it provides a nice mix of durability and high water flow rates. 

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09/29/2023 11:06 pm GMT

The Benefits of Using Filter Fabric for Your French Drain

1. Prevents clogging and blockages in the drainage system

One of the primary benefits of using filter fabric for French drains is that it can prevent clogging and blockages in the drainage system. Without a filter fabric, sediment, debris, and other unwanted materials can enter the drain and cause blockages over time. This can lead to a backup of water, which can cause damage to your property or even flood your basement.

By using a filter fabric, you create a barrier that prevents these unwanted materials from entering the drain in the first place. This means that your drainage system is less likely to experience clogs or blockages over time, making it more effective at removing water from your property.

2. Filters out sediment, debris, and other unwanted materials from entering the drain

Another benefit of using filter fabric for French drains is that it filters out sediment, debris, and other unwanted materials from entering the drain. The filter fabric acts as a barrier that only allows water to pass through while blocking larger particles like dirt or leaves.

This is important because if these particles were allowed to enter the drain they could accumulate over time and create clogs or blockages. By filtering out these particles before they enter into the drainage system itself with a filter fabric, you can help ensure that your French drain operates smoothly for longer periods without needing repairs.

3. Increases the lifespan of your drainage system

By preventing clogs and filtering out unwanted material with a filter fabric, you’re also increasing lifespan of your French drain. When there are clogs or backups caused by neglecting these maintenance measures (such as dirty filters), then not only will there be more frequent repairs needed but also potentially expensive replacements.

With proper maintenance measures such as regular inspections/cleanings of the drainage system and replacing old or damaged filter fabrics as needed, one can be sure that their French drain will remain effective at removing water from their property for longer periods without needing costly repairs. In this way, a filter fabric is a valuable investment in the lifespan of your French drain.

How to Install Filter Fabric for French Drain

Here, I’ll just run quickly through some of the steps to install a French drain so that you can fully see how geotextile fabric fits into the whole process.

If you’re in the planning phase of your French drain project, make sure to check out my list of common French Drain mistakes here.

1. Excavation

The first step in installing filter fabric for a French drain is to excavate the area where the drainage system will be installed. The depth and width of the trench will depend on the amount of water that needs to be drained and the size of the drainage pipes.

A typical trench depth ranges from 18 inches to 24 inches, while the width can vary from 8 inches to 12 inches. It is important to ensure that your excavation process is properly done so that you do not damage any underground utilities such as power cables, gas or water lines.

Laying Down the Gravel Base

After excavation, lay down a layer of gravel at the base of the trench. This helps in providing proper drainage and prevents water pooling around your foundation.

The thickness of this layer should be anywhere between two and four inches depending on how much standing water you expect in that area. It is recommended that you use crushed stones as opposed to rounded ones because they create a better interlocking effect, which improves stability at all times.

Placing Filter Fabric on Top of Gravel

Next, put your filter fabric onto your gravel bed but make sure it is not wrinkled or folded excessively as this may hinder its effectiveness. While laying down this layer, make sure there are no overhangs over the sides; otherwise, debris may accumulate there eventually leading to clogging/blockage issues. Make sure you have enough fabric so that it can wrap around all sides evenly before adding any more layers or materials on top of it.

Filling Up with More Gravel

Once you have laid down the filter fabric correctly, add another layer of gravel on top until it reaches about an inch below ground level. This ensures proper drainage while also preventing soil erosion around your foundation and the drainage system. Be careful not to damage or displace the filter fabric while adding more gravel, as this can lead to a lesser quality filtration process.

Maintenance Tips for Filter Fabric in French Drains

Inspecting and Cleaning the Drainage System Regularly

Once you’ve installed a filter fabric for your French drain, it is crucial to maintain it regularly. Some homeowners make the mistake of thinking that the filter fabric will last forever. However, over time, sediment, debris, and other unwanted materials can accumulate on top of the fabric and eventually clog up the drainage system.

To avoid this problem, you need to inspect and clean your system regularly. The frequency of cleaning depends on several factors such as rainfall intensity or proximity to trees or plants.

It’s recommended that you check your French drain system at least twice a year – once before winter and once after winter – but it may be necessary to do it more frequently if you live in an area with high rainfall or heavy soil load. Cleaning the drainage system involves removing any debris from the surface of the filter fabric, and flushing out any sediment buildup with water from a garden hose or pressure washer.

Replacing Old or Damaged Filter Fabrics as Needed

Even with regular maintenance, your filter fabrics may eventually wear out due to age or damage caused by external factors such as tree roots. When this happens, you should replace them immediately to ensure that your French drain works efficiently.

To replace a damaged filter fabric:

  1. Dig up around the area where the damaged fabric is located.
  2. Remove any gravel covering it.
  3. Cut off any old zip ties holding down the old fabric.
  4. Remove all remains of damaged filter fabrics.
  5. Replace with new high-quality geotextile material
  6. Secure new geotextile material with zip ties
  7. Fill in the gravel

Remember that using substandard filter fabrics can cause more harm than good in your French drain system – they won’t last long enough and may actually promote clogging and blockages instead of preventing them. So always choose high-quality filter fabrics for your French drain system to ensure maximum efficiency and longevity.

non-woven geotextile filter fabric

Conclusion: Wrap Your French Drain with Filter Fabric for Success

Using filter fabric in your French drain system is a crucial step toward its success. The filter fabric acts as a protective barrier that prevents sediment and other debris from entering the drainage system and disrupting its functionality.

Without this layer of protection, your French drain will be quickly clogged and unable to fulfill its intended purpose.

The best type of fabric for a drain field or French drain project is non-woven geotextile landscape fabric.

By installing the filter fabric properly, you can increase the lifespan of the drainage system while decreasing the chances of clogging or blockages.

The filter fabric will help to maintain a clear and unobstructed path for excess water to flow away from your property. It is important to remember that regular maintenance of your French drain, including inspection and cleaning, is necessary to ensure that it continues to function at optimal levels.

Additionally, if you notice any damage or wear to the filter fabric, be sure to replace it as soon as possible. Overall, with proper installation and maintenance techniques in place, adding a filter fabric layer is an effective way to ensure a successful French drain system that will protect your property for years to come.

thewriteDuffy

At home, April is a mom, wife, and DIY darling. Among other home projects, she helped her husband Dan renovate their 1986 bungalow and is currently designing and decorating the 2023 custom home they are building themselves. Professionally, April is a writer, author, and online marketer with 15 years of experience writing for newspapers and magazines, building online authority websites, and publishing books.