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What is a French Drain and How Does it Work?


If you’re in search of a logical solution to properly drain water from your yard, then a French drain may be the choice for you. This gravel-lined trench will allow water to flow off your property by following the path of least resistance. It’s a simple but elegant way to keep your yard dry.

What is a French Drain?

A French drain is a trench, lined with gravel or small rocks, which is designed to direct water away from an area through a perforated pipe. A French drain can help property owners to prevent water from pooling within their yards. It’s a drainage solution that, despite everything implied by the name, has nothing to do with France.

The name “French drain” is conjectured to originate from a farmer by the name of Henry French. He designed the primitive version of the modern French drain when searching for a way to drain water from his crop fields back in the 19th century.

French drains can be used to solve a few different flooding dilemmas by directing water away from your property. Beyond that, they look beautiful and don’t require you to alter the landscape of your property in a significant way. You can even add colourful landscaping rocks to the top layer of the drain to give it some added appeal.

What is a French Drain and How Does it Work?

How a French Drain Works

Directing surface water away from your property is a great way to keep the water level down. A trench drain system, such as a French drain is one of the best ways to do it. The entire design starts with a sloping trench that is at least half a foot wide. Next, the soil needs to be packed down before adding anything on top. From there, you can add a base layer of gravel, perforated piping (weeping tile) to drain the water, and a layer of landscaping cloth on top.

Once the trench is constructed, you have the choice to put sod, gravel, or other rocks on top until the entire trench is level with the rest of the yard. One important thing to note about the functionality of a French drain is that the holes in the piping need to be on the bottom. The holes will allow water that rises from the ground, to drain faster.

During heavy rain, water from the ground will rise and enter the pipe of your French drain. Since the trench is sloped downward, the groundwater will naturally flow to the end of the drain until it’s safely off your property. When planning your French drain, be sure to double-check that the pipe will lead the water to a sewer or some other kind of appropriate drainage destination.

When do you need French Drain

When You Need a French Drain?

If you’re having any major flooding problem on your property, then a French drain may be the solution for you. Not only is it an effective draining solution, but it won’t detract from the overall appearance of your home and lawn. Consider a French drain if you’re dealing with one of the following situations:

Does Surface Water Accumulate on Your Lawn?

Having a wet lawn may seem like a harmless situation in and of itself, but you should not leave it unattended. If you have a lot of surface water which is failing to drain from your lawn, you may be putting your home at risk for major flooding down the line. Install a French drain to divert surface water and protect the investment that is your home.

Your Patio Experiences Flooding After Heavy Rain?

Outdoor patios are a great place to relax and be outside during the warmer months. However, poor surface water drainage can quickly put a damper on your outdoor party plans. On top of that, patio flooding is just one step on the way to having a water leak into your home’s foundation or basement.

By adding a French drain to your home, you can direct excess water off your property and away from your patio. Keeping your patio and yard dry will also prevent mosquitos and other pests from breeding right by your home.

Basement Flooding is a Recurring Problem?

One of the best ways to prevent basement flooding is to minimize the amount of surface and groundwater that gets near your home. A French drain may not be a cure-all if you have existing foundation problems. However, it can certainly help to direct lots of water away from your home. If you experience flooding as a result of water build-up during heavy rains, try using a French drain to prevent water accumulation on your property.

Flooding is Damaging the Foundation of Your Home?

While you may not have experienced major basement flooding yet, it’s entirely possible that poor drainage on your property can cause water to damage your foundation. Go into your basement and give the walls and frames a once-over for any visible signs of damage. A moldy or musty smell may also indicate that the surface water or groundwater on your property is harming the lower levels of your home.

While foundation damage may not be the easiest to spot, a French drain can do wonders for preventing it in the first place. It can end up saving you hundreds of dollars in damages that would happen as a result of water harming your home’s foundation and getting into your basement. Install one so that you can prevent floodwater from ever reaching your home.

Be sure to install a French drain that is suited to the specific problem that you’re having on your property. For example, surface water drainage can be provided by a shallow French drain. More extreme groundwater flooding is best managed using a deep French drain. Consult with a professional before attempting to add a French drain to your property, as this will yield the best possible results.

A French drain may be the solution just right for your situation in providing flood protection for your home.


Paul S

Paul has more then 20 years in basement waterproofing and plumbing projects experience. Looking for an advice from an expert plumber? Make sure to read Paul's articles about residential waterproofing and plumbing projects in Toronto.

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