How much does it cost to install a French drain?

Reviewed by Cristina Miguelez remodeling expert. Written by Fixr.com.

If you have a soggy yard or water that seeps slowly into your basement, you may want to consider the installation of a French drain to dry things out. A French drain is a very simple setup that helps water drain, redirecting it from where you do not want it to somewhere harmless like a sewer drain or street.

Many types of French drains exist. The size, length, depth, and location of the drain all impact the overall cost of the project. Most homeowners installing one in their basement spend around $5,000 for 100 linear feet of drain. The average cost to install French drains range from $2,800 to $6,500. Costs can be as low as $500 for a 50 linear foot drain in an exterior location to as high as $18,000 for an extensive 100 linear foot perimeter drain to stop basement flooding.

French Drain Cost

What Is a French Drain?

French drains are a straightforward solution that involves digging a trench through the affected area, lining it with gravel and weed-blocking fabric, laying perforated pipe, and covering it up with more gravel. Water enters the pipe and is carried away to the designated emptying area. This system works well in areas with pooling water and can be situated within gravel, dirt, or underneath concrete.

They can be shallow or deep and installed in your yard, around the perimeter of your home, or inside your basement. These drains may divert groundwater or surface water, depending on the setup. They can be installed alone or paired with a sump pump for very wet areas. The cost is worthwhile for many homeowners because of the efficient design featuring an excavated trench and a perforated pipe.

Interior vs Exterior French Drain

Most French drains can be categorized as either interior or exterior. From there, they also break down slightly further into more specialized categories that address specific needs. Below is a breakdown of the types of French drains and the average cost for each minus installation.

Exterior French Drain

The costs to install an exterior French drain runs between $10 and $100 per linear foot. Exterior drains come in two types - shallow and footing. Shallow drains are most common for draining a soggy yard and are less expensive in general. Footings go around the perimeter of your home and are very deep, often several feet, which causes the costs to increase considerably. They will be visible, so it is common to add decorative pebbles and a curb.

A shallow French drain is similar to a deeper one in the way it operates. The only difference between the two is that the shallow kind will be closer to the surface, often having only about two inches of gravel. Shallow systems are ideal for areas without a significant amount of water or are not in areas with an extremely high water table. The average cost for a shallow system is $10 to $50 per linear foot.

Exterior French drain footing drains are created by leaving a gap between the floor and the wall, which will direct the water down to the drain. It helps route water from seepage through windows, cracks in the walls, or even high condensation levels. It helps keep water out of the basement in the event of a flood. It can be a good option for basements that see regular water accumulation but can become clogged the same as the other types. Deeper footing options are more expensive, often running between $80 and $100 per linear foot.

Interior French Drain

Interior drains need a sump pump to be truly effective. Interior French drain cost for a linear foot runs between $40 and $100. Larger basements require two interior drains, which involve digging a small channel in your concrete to lay the pipe and then covering it with a thin layer of concrete. If interior walls are in the way, they need to be at least temporarily moved for installation.

These are very effective at preventing water infiltration into the home. They can easily be installed in existing homes and new builds. The drawbacks are that they can be expensive and invasive, often requiring cutting through concrete and walls.

French Drain Cost per Foot

The French drain’s cost per linear foot depends on whether the drain is installed in the interior of your home or the exterior. On average, for exterior installation, you can expect to pay anywhere between $10 and $100 with an average price of $25 per linear foot. A French drain for internal installation costs from $40 to $100 per linear foot or an average of $50 per foot. Below is a table showing the average cost of some of the most common sizes, including the cost of installation.

French Drain Pipe Cost per Inch

Most French drains utilize a perforated pipe buried in the gravel of the trench to help direct water that is captured to another location where it can be absorbed into the ground. Pipes are most commonly made out of plastic, primarily for their durability and flexibility. These pipes come in a variety of diameters. The best width will be determined by how much water or how heavy the rains are in your area. Below is a table of some of the most common diameters and the cost of each per linear foot for materials only. The diameter does not significantly impact the overall cost of the installation compared to the pipe length.

Labor Cost to Install a French Drain

Most French drains are installed in roughly the same way. A trench is dug in the affected area, with the width and depth dictated by its location and how much water needs to be drained at a time. Once the trench is dug, it is lined at the bottom with gravel and then covered with a fabric weed blocker. The drain, usually perforated PVC but may be flexible hosing, is laid in the trench and covered with more gravel. If desired, soil may be backfilled on top. French drain pipe costs range from $0.70 and $3 per linear foot. The process is similar for basements, however, the finished drain is usually covered with a thin layer of concrete for strategically placed drains.

In some cases, connecting a French drain to a storm drain can be the best option, as it allows the water to flow out to an appropriate location along with other rainwater. If you have a storm basin on your property or just across your property line, connecting to it can be easy and inexpensive, often costing between $100 to $200 to have the lines coupled together.

The French drain price for the system includes both labor and materials. Labor and material are grouped by installers, with labor making up the larger share. Labor rates are often charged per linear foot but can be charged with hourly rates between $35 and $75 per hour. The cost to install an interior French drain is usually higher than an exterior one due to excavation requirements. For an interior basement drain, the average French drain installation cost per foot is $50, with labor making up about $35 to $40 a linear foot and material making up the rest. For 100 linear feet of installation, this makes labor about $3,500 to $4,000, making the average installation cost between $5,000 and $6,000. The cost to install an exterior French drain is about $35 per linear foot. Labor comprises about $20 to $25 a linear foot, and the rest goes toward materials for a total of around $3,500 to $4,000.

Install a Sump Pump and a French Drain

For homeowners with basements prone to water throughout the year, a combination sump pump and French drain may be the answer. The sump pump is a small device installed in a corner of the basement or lower-lying areas. They are designed to sit in sump pits with the sole purpose of removing water to keep your basement dry. When combined with a French drain, the water flows into the pit and is pumped out by the sump pump into the drain. Here, it will be carried away from the house. If you install a combination sump pump and French drain, it will cost around $65 to $75 per linear foot, depending on how many pumps the area requires. You may get a slightly cheaper drainage system cost when the installation is done at the same time as a sump pump. However, it depends on your installer and the complexity of your system.

Cost to Replace a French Drain

The costs for French drain replacement vary widely, depending on what damage has occurred and what needs to be redone. If the pipe is damaged and needs to be replaced, you can expect the project to take between three to six hours. This French drain repair cost ranges from $1,000 to $2,500. If the whole area needs to be retrenched and replaced, it can take up to ten hours and cost almost the same as installing a new one. The price ranges from $2,000 to $8,000.

If there is standing water in the drainage ditch or water flowing over the drainpipe even after the pipe has been inspected for clogs, then your system is no longer working properly and may need to be replaced. Even well-maintained systems become damaged over time, and broken pipes may become clogged with silt and debris, making it more difficult for the water to move through. You may find that the depth is no longer effective for the water table level and needs to be adjusted.

Average Cost to Install a French Drain by Location

French drains can be installed in several spaces but are most effective when used properly, in the appropriate location, and at the correct depth. When used outdoors, they work best on slopes or downhill areas of your yard, as this assists with drainage. When used primarily to keep water out of the basement, they are best located around the perimeter of the foundation. While the average cost of a French drain is around $5,000, the total cost depends on the length and location. Your professional installer can get you an accurate quote for your specific home needs. To give you a better idea of what to expect for your installation project, the below table highlights the average cost of building a French drain by location.

Install a French Drain in Yard

On average, the cost of French drain yard installs run between $20 and $30 per linear foot. When installing this system in the yard, the most common placement is around the perimeter of your home, though they can be placed in almost any area they are needed. If water in the front of the house is a problem, the drain will often be installed along the front of the foundation with a path that pulls the water around the house. They can also be used in other areas of the property where water buildup tends to be a concern. The cost to install a French drain in the backyard will not be costly as long as the yard is clear of any structural components or utility lines in the way of placement.

Install a French Drain in Crawl Space

On average, a homeowner will pay between $25 and $35 per linear foot for installing a French drain in the crawl space. This step can be an important part of waterproofing basements. Since the trench will be dug in the ground, it can be less expensive than interior options. However, the cost increases when you have to work around the crawl space and remove temporary structures. This can be ideal for areas with heavy rains and a high water table.

Around Patio

Installing this type of system around the patio will cost approximately $25 to $40 per linear foot installed. They solve the issue of water pooling around the area. Pooled water on the patio becomes problematic because it can cause swampy yards and attract insects. Water exposure around the patio can damage the stone or other material used to make the structure. The drain will start at the patio where the water pools and runs to lower ground.

French Drain Along Retaining Wall

You can expect to pay anywhere between $25 and $50. If you have built a retaining wall on your property, installing a French drain protects the integrity of the wall. Without one, water moves down the hill and builds up behind the wall, putting pressure on it. Typically, it will be added behind the first course of blocks or stones that back up the base. The pipe used will reside in the same compacted gravel or concrete base footing that supports the wall. The cost to install a French drain along a retaining wall varies depending on the wall materials and the landscape surrounding it.

Under Sidewalk

A French drain under the sidewalk will cost around $30 to $50 per linear foot installed. The extra cost is from the need to dig under the sidewalk for the installation. Sidewalks usually measure 4 inches deep, requiring the hole to be dug to that depth. Homeowners choose the area under a sidewalk for several reasons. For one, you may be trying to hook up a pop-up emitter set at the curb. This set-up is an alternative to traditional grates and keeps debris out of pipes. Another reason for a French drain to go under a sidewalk is to extend the downspout through your yard.

Under Deck

You can expect to pay anywhere between $35 and $45 per linear foot to install a French drain under a deck. This location helps protect your home’s foundation, reduces the risk of water in the basement, and preserves the deck’s integrity. The cost of installing the system in this location can be higher than installing one in a yard because it may require removing part of the deck.

In Driveway

The cost to install a French drain in the driveway runs between $45 and $55 per linear foot. Though not as expensive as installing it indoors, installing one in a driveway can be costly, especially if it is already there. With the removal and relaying of concrete costing around $2 to $6 per square foot, it can add around $200 to $600 to the total cost, or even more depending on the size, shape, and elevation of your driveway. But if you have standing water in your driveway, drainage is important to prevent wear to the concrete or poor driving conditions in areas with freezing temperatures.

Garage French Drain

Homes with driveways that slope into the garage benefit from this drainage system. Installation costs for the driveway run between $50 and $60 per linear foot. The cost to install this type of system in the garage is almost the same as installing one in the interior of the home. The higher cost involves additional labor to tear the concrete up in the garage and replace it once the drain has been installed. Having one installed keeps water from coming through the garage to the home’s foundation.

Install a French Drain Around House

This option can be expensive, running between $50 and $80 per linear foot. Prices can be affected by structures, utility lines, and landscaping that is likely to be around the outside of your home. If you have a small amount of water in your basement, you can install it around the perimeter of your home to help channel away any groundwater that seeps through your basement walls. If you need a French drain along more than two walls in your basement, this is the better option. It may need to be fairly deep, depending on the height of your basement walls.

Basement French Drain

The cost to install a French drain in the basement runs between $60 and $70 for professional installation. They help reduce hydrostatic pressure, which is exerted by fluid due to the force of gravity. This pressure causes high water around a home to become forced into basement areas leading to flooding and water damage.

If you have water inside your basement frequently, you can install a French drain inside your basement floor and pair it with a sump pump. In this situation, the channel will be installed inside your concrete floor. The water will be directed to a pump pit, where it can be safely pumped out of the house.

Inspection

When you install a French drain, you need to have an inspector ensure that it is installed properly, within regulation, and performing correctly. During an inspection, the inspector checks to see that the expelled water does not disturb the adjoining properties or is not at risk for a flooding lawsuit among neighbors. They will check to ensure that the water being expelled is not contaminated and within the lawful limits. Costs for a French drain inspection run between $150 to $250 depending on the length of the French drain and the inspector’s charges for the service. This cost will be in addition to any installation and material costs.

How Deep Should a French Drain Be?

French drains can be dug depths ranging from a few inches to several feet. The depth depends on the drain’s location and how much water is in the area.

If you plan to install one in your basement and have a high water table, you should make sure that the depth is between seven and nine inches. You can go as deep as eight to twelve inches if you have a layer of iron ocher just below the basement floor.

When considering the depth for an exterior installation, the minimum effective depth is usually eight to 16 inches below the level of the basement floor. Depths can go lower, especially if you have a low-lying area or experience heavy rains and flooding in the area.

When to Install a French Drain?

French drains are most useful when you have slow-moving or slow-collecting water. If you have sections of your yard that are always soggy, water that seeps slowly into your basement or crawl space, or water that collects in your driveway, these are signs that you need a drainage system. If this is the case, a it may be a good solution for you.

Other times to consider installing a French drain is if you have a retaining wall on a hillside. This could lead to more water by the foundation of your home. A drain could be necessary to pull it away. You also may want to consider them if your property is lower than the properties surrounding you or if your foundation is lower than the land surrounding it. Without a proper drainage system, you may find water is being directed toward your foundation.

Where to Install a French Drain?

French drains can be installed inside or outside of the home, depending on where you have standing water and the severity of the issue. If you have an area in the basement that gets more water than the rest of the basement, you may want to consider installing one of these along one or two walls. If you find that you need drains along more than two walls to solve the problem, then it is advisable to have a perimeter French drain installed around the outside of your home.

Whether you install them inside or outside, the ideal slope is one inch for every eight feet. It should never have a slope that is less than 1%. A French drain with no slope will be ineffective at pulling water away from the home.

Discharge Options

One thing to consider when installing your French drain is where you want the water to drain out. If you live close to a street with a proper storm sewer drainage system, you can direct the water out into the street. If you have a heavily grassed area on your property where the drainage is good, you can direct it there, or you may tie the drain directly into a nearby sewer line, depending on its location.

If you don’t have any of the above options, you may need to consider creating an area for your water. Rain gardens are a popular way to end them and cost around $1,000 to $3,000, depending on size. The area is depressed and collects water from the drain, using it for plants that do well in these conditions like grass and flowering perennials. Irrigation ditches are another option for water discharge, delivering water to surrounding land, particularly dry areas such as farm fields. They may be used alone or with a French drain and cost around $0.50 to $1 a square foot.

A final option to consider is constructing a dry well. These large reservoirs are often designed with holes in them and submerged in gravel at the end to allow water to drain out slowly. The water is absorbed in the ground without causing a back up. Dry wells can be made from several materials, including plastic, concrete, and loose stone. The cost to install a dry well varies depending on the material being used and cost between $1,500 and $5,000.

Pros and Cons

As with any type of drainage system, French drains come with both pros and cons. One of the advantages is that they allow for efficient drainage, directing water away from the foundation of your home. You decide where you want the water to be transported and combine it with a sump pump to keep your basement and foundation dry. They are extremely affordable when compared with other methods for waterproofing your basement. Another benefit is that a French drain helps spongy lawns get the drainage they need to stay firm.

While there are many advantages to installing a French drain, a few drawbacks can be noted. One of the primary cons is that some installations may be difficult. If it is installed around gas lines, water lines, or other underground utilities, it can cause safety concerns. An installation may also become problematic if there has to be the removal of certain structures, such as porches and sidewalks. Another drawback is that they become clogged. Even well-designed systems will eventually become clogged with mud and debris and require annual maintenance to prevent the water from backing up.

French Drain Cleaning Cost

Regular maintenance keeps your drain functioning properly and allows it to last for a much longer time. To keep it properly maintained, it should be professionally cleaned out at least once a year. You may need to have it cleaned more often if it seems to be draining slower than normal.

No matter how well your French drain was installed, it will eventually become clogged with dirt, debris, and silt. This can cause it to drain more slowly, making it harder to keep water away from the foundation. When this happens, you need to call in a professional who uses an electric snake to clean the drain from built-up debris. Interior French drain maintenance is extremely important since it can damage your indoor plumbing system. Check the status often to confirm that there are no visible drainage issues.

The process for cleaning the drain can take one to three hours, depending on the severity of the clog and length of the drain. Most professionals charge between $45 and $150 per hour. An average cost range for snaking this type of pipe is $75 to $500.

French Drain vs Curtain Drain

Curtain drains and French drains work in similar ways. The biggest difference is that curtain drains are always very shallow, dealing mainly with surface water, while French drains are usually deep enough to handle groundwater or surface water. They are installed in the same manner by digging a long trench to direct water to another location through a piping system. Another difference between the two is the location of their installation. French drains are normally installed around the perimeter of a home to draw the water away from the basement. Curtain drains are typically installed in the front of and slightly around the house to divert the water before getting to the basement. Curtain drains run between $10 and $25 per linear foot for a total around $1,000 to $2,500, while the average per linear foot for French drains is $10 to $100 for exterior, or $2,800 to $6,500 on average per project.

French Drain vs Trench Drain

While both French and trench drains are designed to remove water, the type of water they remove and how quickly it is removed make them quite different. French drains are designed to capture groundwater and transport it along a perforated pipe where it will absorb into the ground along the way. Trench drains remove surface water quickly before it begins to absorb into the ground. Trench drains can be significantly more expensive than French drains, averaging anywhere from $30 to $150 per linear foot or $3,000 to $15,000 per project installed compared to $10 to $100 per linear foot or $2,800 to $6,500 per average project for French drains.

French Drain vs Catch Basin

Though sometimes lumped together, French drains and catch basins are completely different systems. They are often used together to create a more robust waterproofing system. While French drains are subsurface drains, catch basins are surface-level drains. They are connected to either a box or basin where water can be collected quickly and transported to another area. Catch basins are less costly than French drains, running between $2,500 and $5,000 for the complete project compared to $2,800 to $6,500 for French drains.

French Drain vs Sump Pump

Sump pumps are designed to pull water out of basements from low lying areas prone to collecting water. They can be less expensive than an interior French drain, costing between $700 and $1,600 on average instead of $2,800 to $6,500 for French drains. Unlike French drains, they rely on electricity, which can become a problem if the power in the home goes out during a storm. Sump pumps are not designed to keep water away from the entire basement and are better suited for targeted areas. Conversely, French drains are designed to draw water away from the entire basement.

French Drain vs Swale

Swales are ditches that are concealed with vegetation to collect surface water over an expanse of land. They are designed to have a subtle appearance and blend in with the natural landscape of the area. They are similar to French drains because they’re both designed to drain water. Swales are a general-purpose drain, where French drains are designed to draw water away from a home’s foundation. Swales are typically only found on larger lots.

One of the pros of swales is that they can be very inexpensive, depending on the material used. If using vegetation from seed, the cost will be between $4.50 and $8.50 per linear foot. When using vegetation from sod, the costs go up to $15 to $20 per linear foot. The average project cost of $450 to $2,000 for swale drains is cheaper than the average $10 to $100 per linear foot or $2,800 to $6,500 per project for French drains. Swales can be a popular option because of their longevity, often lasting up to 50 years with minimal maintenance. One of the biggest drawbacks to swales is that they may not withstand heavy storms. They are not advisable for steep areas and can create a clogging risk for nearby pipes.

Enhancement and Improvement Costs

Crawl Space Encapsulation

Encapsulation systems can be as simplistic as single-layer thin plastic coverings and as high-end as heavy liners with multi-layered vapor barriers. These more advanced systems would also include a dehumidifier, sump pump, and drainage trenches. Installing a crawl space encapsulation after installing a French drain can block out moisture and pests, maintaining the integrity of the space. The average cost to install a crawl space encapsulation is $5,500, including supplies and labor costs. On the low end, you can expect to pay $1,500, and the high range of costs goes as high as $15,000. The price varies based on the size and condition of the space, the contractor’s rates, and the materials used.

French Drain Retaining Walls

If you have a lot of water in your yard, it can cause soil erosion. If this is the case, you may want to install a retaining wall to assist. Retaining walls can be constructed in several ways: interlocking concrete blocks to form a wall or pouring and stamping concrete. Dry stack retaining walls and poured concrete walls cost $20 to $25 per sq.ft.

Vertical French Drain

Some yards with water issues benefit from installing a dry well, a hole filled with gravel that collects and drains water. These are sometimes called vertical French drains. They have lower costs but are less effective at keeping water away from your home. They start around $100 to $300.

Additional Considerations and Costs

• Permits. Interior and exterior French drains may require permits. This permit is likely to cost between $50 and $100. Check with your local town or city hall for more information about costs and what may be needed in your area.
• Utilities. Always call your utility company or 811 before digging in the yard to find out if you have utility lines nearby. The drain may need to be relocated if this is the case.
• French drains vs ground gutters. Ground gutters are generally shallower, while French drains may be deep or shallow, depending on the need. Ground gutters also typically run to a dry well for collection, which may be lined with a membrane to contain the water more effectively. Or, they may simply allow the water to drain naturally. French drains typically terminate at a sewer, street, or into an area better equipped to handle the water.
• French drain vs drain tile. French drains and drain tiles are similar in their function, but where they are placed and their output makes them different. A French drain is installed just below the ground’s surface and moves water from spots where it may collect. Drain tiles are installed eight to ten feet below ground around the foundation footings and drain groundwater away from the foundation. Drain tiles can get expensive depending on the size of the area, ranging from $10 to $30 per linear foot.
• Landscaping factors. When installing this type of system, some considerations will need to be made in terms of landscaping. Since the trench will often be at least several feet deep and a few feet wide, you need to determine if it can be worked around landscaped areas, such as fences, sidewalks, gardens, driveways, trees, and shrubs.
• Prefabricated French drain. They are designed for easier installation. Pricing will be similar to typical installation jobs because although the material is more costly, less labor is needed for the projects. Every 10 ft. section of prefabricated pipe will cost around $50.
• Hydroblox. Hydroblox is a newer system used in place of French drains. Instead of laying pipe, Hydroblox is placed down as planks. The surface is designed to pull in and carry water away from the home. Each panel made from recycled plastics is equivalent to a 4-inch pipe. Hydroblox has an average cost of $1 per foot installed.
• Landscaping repair. When you install a French drain, your landscaping may suffer. Holes are dug in the yard, and shrubbery and plants may become damaged in the process. Expect to pay between $50 and $100 per hour for the use of professional landscaping services.