If you have a swampy yard, someone may have suggested installing a French drain. If you’ve ever wondered, “What Is a French drain?” this is the post for you. We’ll answer the question how does a French drain work, review French drain construction, and explain why French drains and similar solutions are essential if you have drainage problems. What is a French drain and how does it work?

The Headaches and Dangers of Having a Swampy Yard

Too much water in the yard can be more than just a nuisance; it can cause serious damage to your home as well as a long list of other landscaping hassles. At the very least, a swampy yard can be messy, causing kids and pets to track in mud — if they can find a place to play outdoors. It can ruin your hard work and investment building a garden because plants can’t root well and are subject to rot and pests.

Even worse, poor drainage that allows water to collect near the structure of your home can result inlong-term damage. The foundation can become compromised, leading to instability and collapse. This makes the property unsafe, lowers its value, and may render it impossible to sell if it’s on the market.

Water can make its way inside the residence as well. This can cause water damage andmold. Aside from the expense of repairs, mold brings with it significant health concerns, including asthma attacks and infections. It can make the home smell musty, as it contaminates the air you breathe.

What Causes Too Much Water in the Yard?

Inadequate drainage can be caused by a number of factors, sometimes acting in concert with each other. These are the most common ones we see:

  • Excess of hardscaping (asphalt, patios, and other impervious surfaces)
  • Compact soil, especially high in clay content
  • No roof gutters or gutters are clogged
  • Blocked downspouts or downspouts empty in a bad location
  • Landscape elements blocking the flow of rainwater
  • Poor yard grading that channels water in the wrong location

在这些scenarios, rainwater and snowmelt wind up accumulating in a “pond” in the yard, or they collect around the home’s foundation rather than being absorbed into the ground.

What Is a French Drain and How Does It Work?

So what is a French drain and how does it work? The French drain isn’t named for the country of France. Rather, it is named for agriculturalist Henry Flagg French, who invented the concept and wrote about it in his book “Farm Drainage” in the mid-19th century. French’s son, Daniel Chester French, created the Lincoln Memorial in Washington, DC, where his father’s drain was used to protect the base of the monument.

Fast forward more than 100 years later, and French drains are still used today because they’re a simple solution to a common drainage problem. Property owners around the country use them to prevent damp basements, flooded crawl spaces, and swampy yards, especially when constructing retaining walls.

Think of a French drain a bit like a roof gutter underground. It uses the flow of gravity to aid in the transport of water from one area — most often the soil around a building’s foundation — to another, more convenient one.

A French drain is made up of a trench lined with gravel surrounding a pipe. The pipe is either perforated or has inlets at set intervals along its length. This allows the pipe to collect water from the soil nearby. The water then runs downhill through the pipe to wherever the property owner wants it to go. As discussed below, this may be a dry well or Flo-well. It could also be a pond or water garden, for example.

Common Questions About French Drains

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

These two drainage solutions are very similar. However, a French drain is designed to absorb water slightly below the surface, whereas a trench drain collects runoff from above the surface of the ground.

How deep does a French drain need to be?

The depth of a French drain depends on its specific purpose and where you install it. Sometimes they’re buried just several inches to a foot below the ground. When water is seeping into your basement, though, a French drain (also called a footing drain in this usage) must usually be deeper to reach thefoundationfooting.

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

The complexity and size of the drain often determine much of its cost. Shallower drains installed in a yard typically only run property owners the cost of gravel (per cubic foot) and pipe (per linear foot). Labor is minimal in these jobs, particularly if you’re already doing landscaping for regrading a slope or building a retaining wall.

In more complicated jobs, there is more digging involved, and the French drain may connect with a basementsump pump. Also, the drain is larger, often around the entire perimeter of a foundation. Once we evaluate your unique drainage needs, we can give you a detailed estimate for the cost of French drain installation, which can range from several thousand dollars to over ten thousand dollars.


A French drain should last at least 10 years, although it often has a lifespan of three or four decades when properly maintained. Sometimes sand or silt infiltrates the pipe over time, making it eventually useless. But the advent of protective sheeting can help prevent pipe infiltration, so you can get many more years from your French drain. Professional installation can also give you a longer drain lifespan.

How often should French drains be cleaned?

You should plan on cleaning out a French drain about once per year. This is done manually with a snake tool to remove soil, detritus, and roots that invade the pipe.

Can you cover a French drain with dirt?

Yes, some French drains are carefully covered with soil. This allows property owners to better disguise them with nearby landscaping elements, so they blend in.

What Are Some Alternatives to a French Drain?

Sometimes a French drain isn’t quite the right solution for your property’s drainage problem. In that case, there are other options you can try, alone or together, to eliminate excess water:

  • Installing gutters and redirecting downspouts
  • Collecting rainwater in barrels
  • Installing a sump pump
  • Reducing hardscaping and adding more porous surfaces
  • Lawn aeration and soil improvement
  • Planting a water garden or adding a creek bed
  • Regrading the yard
  • Adding dry wells or Flo-wells

Dry wells are catch basins buried underground to collect water at the top. They have holes in the lower portion of the container that release the water into the soil at a slower pace and at a more desirable depth. A Flo-well is simply a much larger version of a dry well that can hold 49 gallons of water at a time. Dry wells and Flo-wells work very nicely together with French drains and can serve as repositories for the water collected in French drains once it is channeled to a new area.

DIY Versus Professional French Drain Installation

You can install a small French drain yourself if you know what you’re doing and have the right equipment. The best way to do this is to experiment in a section of the yard where any goofs on your part (there is a learning curve) won’t be consequential.

If you need a French drain in combination with a retaining wall or along your foundation, however, it’s highly recommended to have the job done by experts. You don’t want to find out a DIY installation is actually making your problem worse instead of better.

At Moisture Loc, we install French drains as part of our menu of home services for property owners, real estate agents, andbuilders. There are several advantages to hiring Moisture Loc professionals:

  • We are experienced, having served the greater Charlotte, NC, area since 1988.
  • 我们的顾客评论攻击力高est to our meticulous service and reliability.
  • We have access to all the equipment and supplies needed to get the job done quickly and efficiently for you.
  • We also provide a range of related services, includingbasement waterproofing, mold removal, and crawl space encapsulation. You can get your entire drainage problem assessed and remedied by the same team.

Is a French drain right for your property’s drainage issues? Still need more information on what is a French drain and how does it work?We offer a free initial consultation so you can learn more. Call Moisture Loc at 704-554-9229, or use our easy contact form toreach out online. Don’t risk the damage that poor drainage can cause. Get in touch today.