Tools and Materials

Tools

Materials

Note

Product costs, availability and item numbers may vary online or by market.

The Purpose of a French Drain

An illustration showing French drain placement around a home.

French drains are underground drainage systems that move water away from the home and other areas. They help resolve groundwater and surface-water issues that can cause damage, such as mold and wood rot that may result from standing water. They also prevent flooding of basements, walkways, patios, lawns and driveways.

Tip

If you’re installing a French drain to prevent basement moisture, make sure to install the pipe below the finished floor or slab level.

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Planning Your Project

Never place the drain outlet where it’ll simply move the drainage problem and runoff water to a different area — especially someone else’s property.
Contact your local authorities if you plan to connect your drain to any municipal, county or state system for drainage, sewer or runoff.
Contact your local authorities if you plan to connect your drain to any creek, stream or other body of water.
Always check your local zoning laws, building codes and homeowners association to ensure you remain in compliance with all regulations.

Installing the French Drain

Before installing a French drain, choose an area for the drain that’s at least 3 feet away from walls, fences, trees or any other obstructions. Mark the location with marking paint.

Caution

Before digging any excavation, call 811 a few days before you dig to check for underground utilities.

How Do I Install a French Drain?

Two men digging a French drain in a backyard.

Dig a trench that’s 9 inches wide and 18 to 24 inches deep. Slope the trench downward 1 inch for every 10 feet of pipe that you plan to install. Be careful to keep the bottom of the trench flat so you don’t have high spots in the corrugated pipe that may hamper the flow of water.

Tip

If you’re digging a long trench, make quick work of the job by renting a trench digger. Contact Lowe’s to check out our wide variety of tool rentals.

A catch basin in the ground surrounded by grass, red flowers and a downspout.

Drill 1/4-inch holes, spaced out evenly in each corner of the bottom of the catch basin, for water flow. Next, dig a hole for and install the basin and basin grate. Before installing the basin, place 6 inches of gravel in the hole to eliminate standing water. The basin grate should be flush with or slightly below the surrounding ground level.

Good to Know

There may be occasions where it’s necessary to install a catch basin in more than one place, such as low areas of the yard.

Test the drain flow by running water into the basin with a hose. If the system doesn’t drain, ensure you’re sloping the trench downward 1 inch for every 10 feet of pipe and adjust as needed.

Tip

Many pipe connections in landscape drainage, including those to catch basins, aren’t designed to be watertight. When you test the system, it’ll leak. Once you backfill the trench and area around the basin, the soil will seal the connections.

Regular Maintenance and Upkeep

After installing your French drain, inspect it — and clean it when necessary — on an annual basis. To determine if your French drain is working properly, look for areas of standing water. If your basement is flooded or you have low areas in your yard that aren’t as firm as the high ground or the ground is soggy or flooded, it’s an indication that your French drain isn’t working properly. Another way to check for a blockage is to flood the drain in the catch basin and see if it comes out the pipe end. If the water doesn’t flow out the pipe end, there’s a clog somewhere in the French drain.

French Drain Installation: How to Install a French Drain