What is a French drain system?

Author: Chasity Terry  |  Last update: Thursday, March 20, 2025

A French drain is a trench filled with a perforated pipe and gravel that allows water to drain naturally from your yard. Depending on the size of your yard and the scale of your drainage issue, you can purchase the pipes and equipment to create a French drain yourself.

What are the downsides of a French drain?

Weeping tile is prone to clogging over time, and may require expensive excavation to correct. French drains that become clogged may overflow without warning and cause damage, such as flooding in yards and basements. Existing structures may need to be removed if a French drain must be excavated.

What does a French drain empty into?

In many cases, it will be recommended that the pipe release the excess water into the street. It will then travel to sewer drains and will be drained away in the city system.

Why would someone install a French drain?

Installing a French drainage system is a good option for homeowners with sloping terrain. The drainage system can direct stormwater away from your property while at the same time preventing clogging and weed growth. It can also be a great way to dry up a soggy yard.

What's the difference between a French drain and a regular drain?

The main difference between the two is that French drains capture and remove groundwater while trench drains quickly remove surface water before it can saturate the ground.

HOW A FRENCH DRAIN WORKS

Where not to put a French drain?

Clay soil has poor permeability, meaning it doesn't allow water to pass through easily. In such cases, the effectiveness of a French drain may be limited as the water may struggle to drain away from the area efficiently. French drains may not be suitable for areas with high water tables.

How much does it cost to put a French drain in your yard?

French drains (aka weeping tile, perimeter drains, agricultural drains, and rock drains) are an easy-to-install solution for your drainage problems. Clients pay an average price of $5,000 to have a French drain installed professionally, with most homeowners paying $1,650 – $12,250.

What works better than a French drain?

Dry wells are another effective alternative to French drains, particularly for properties with poor drainage. A dry well is essentially an underground chamber that collects and temporarily stores runoff water, allowing it to seep into the surrounding soil gradually.

How many years does a French drain last?

Generally speaking, a French drain will last approximately 30 to 40 years. However, the above-mentioned factors may shorten its life cycle and it must then be replaced by a team of foundation experts.

Is a French drain illegal?

If installing the drain involves diverting a stream or affecting a wetland, you likely need a permit to move forward. Generally, a small French drain on your property that doesn't change the flow of runoff entering and exiting your yard won't need a permit.

Does water sit in French drain?

A French drainpipe offers you the solution for if your basement is admitting water through the foundation. In a "wet" basement, the water presses against the foundation, slowly leaking through. However, a French drain reroutes the water near the foundation and releases it elsewhere.

How often do French drains clog?

Just like other types of drains, they are susceptible to clogging over time. Ideally, clean the French drain once every year.

Does a French drain go all around the house?

For foundation problems, the drain should be installed along the perimeter of your home, typically at the base of the foundation. To address wet spots in your yard, place the drain uphill from the problem area to intercept water before it reaches the low point.

Are French drains tax deductible?

With stormwater, most likely, your drainage systems would fall under land improvements. Stormwater best management practices such as french drains, downspouts and gutter systems, bioswales, and dry wells could qualify as depreciable assets.

Why is French drain so expensive?

Interior French drains are meant for waterproofing the basement or draining your crawl space. They cost more because contractors must tear out the basement floor (most often made of concrete), install the drain, and then repair it.

Do French drains cause mold?

Poorly installed French drains can cause water to pool around your house's foundation and seep into the basement or crawlspace, leading to wet floors and walls. This moisture can damage furniture and flooring, and lead to mold and mildew growth.

How far down do you dig a French drain?

Dig a trench from the place in your yard that needs drainage to your chosen outlet. Check for underground utility lines and pipes before digging. The trench should be about 18 inches deep and 9 to 12 inches wide. least 1 percent, so the force of gravity will work for you.

Do French drains add value to your home?

By preventing water damage and maintaining a healthy landscape, French drains can reduce long-term maintenance costs. This is a valuable selling point for potential buyers, making your property more attractive and potentially increasing its resale value.

Do French drains need maintenance?

French drains can be a great way to direct rainwater runoff away from your foundation and septic system, but they require annual maintenance to keep them clear and working properly.

What are the disadvantages of a French drain?

Disadvantages of French Drains

Another disadvantage of French drains is their potential to attract tree roots. The gravel or rock used in the system can provide a water source for trees, leading to the origins invading the drain. This can cause blockages and damage to the system.

How much does it cost for a French drain?

French drain costs range widely (from $500 to $18,000) and will vary based on where the French drain is located (inside or outside) as well as its length and depth. However, most homeowners will pay around $5,000.

Do plumbers put in French drains?

French drain installation is a service offered by a diverse range of professionals from landscapers to plumbers to foundation specialists. These professionals bring a varied skill set to the project, often integrating the drainage system seamlessly with other landscaping or construction work.

Do landscapers put in French drains?

Landscapers have the expertise to work the French drain installation into your existing landscape design, ensuring it not only functions well but also doesn't interfere with your yard's aesthetics.

What is the alternative to a French drain?

An alternative to the French drain, the NDS EZ-Drain installs without gravel, saving a lot of time and money. EZ-Drain bundles consist of fabric, lightweight gravel substitute, and pipe. It's like an entire yard drainage system, bundled neatly together.

What is the difference between a trench drain and a French drain?

Aside from what we've listed here, the difference between a French drain and a trench drain is that a French drain is used for water that is underground while a trench drain diverts excess water from a surface.

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