House Projects

Creating a DIY French Drain

Introduction

We've always had problems with one corner of the house and the gutter downpipe on it. Rain water would run down the pipe, then saturate the lawn. It rarely dried out properly. At times it looked like a swamp or small lake.

Around 2017, I asked a local handyman to install a French drain from the downpipe to run under the lawn. Unfortunately he didn't know what a French drain is and didn't look it up. What he did was get some unperforated 4" pipe and bury that under the lawn with an elbow at the far end with a grating on top of it. What this meant we had water standing in the pipe all the time while the grating became either a heaven for mosquitoes or an unwanted fountain in the lawn. It was a rubbish job.

The first horrible drain The first horrible drain

By May 2018, I was thoroughly fed up with the job the guy had done and decided to dig it up and make my own French drain.

Creating the French Drain

A French drain is easy to make but involves a lot of work. There's a lot of digging to be done and rock is heavy!

From the drainpipe to the garden path through the lawn is about 12ft. I needed to take a 3ft wide section of turf up along the path of the trench, dig a 12ft long, 3ft wide and 3ft deep trench, put about 6" of rock in the bottom of the tranch, lay a 4" diameter, 12ft long perforated pipe and it's sock on top of that.

Cover the pipe with another 6" layer of rock. On top of that goes a layer of landscape fabric. The remaining space in the trench is then half-filled with rock and the fabric is folded over that. The rest of the trench is then filled with dirt and the turf put back.

That was the plan, but the turf was so wet and full of weeds, I decided to reseed it when it was finished.

It's easy! It can be described in just a couple of sentences, if only it was that easy to do!

The pipe sock and the landscape fabric are there to allow only water, not dirt, to travel between the layers.

I got really lucky with the digging. I got a lot of help from a good friend who just so happened to own a rotovator. These things are not trenchers like a Ditch Witch, but they can easily loosen the soil so it can be dug up.

Here's a tip - when the trench is being dug, put the removed dirt on an old tarp. It saves wrecking the rest of the lawn and it's much easier to move what remains.

The trench and in it, the perforated pipe and the layers of rock. Next to all that is the dirt we dug out. The half-buried perforated pipe and its sock. The half-buried perforated pipe and its sock. A layer of landscape fabric put down. Of course Abbie the cat thought it the most comfortable place on earth. Another layer of rock on top of the landscape fabric. The landscape fabric folded back over the top layer of rock. The trench backfilled with some of the dirt we took out of it. The trampled down dirt in the trench and the dirt that was left over.

The finished French drain

The finished French drain and regrown grass

As time went on, everything in the trench settled a little, not by much as I had overfilled it a little when I backfilled it, but enough that I had to add a little more dirt to it while the grass was growing.

Sources & Resources

French Drain - wikipedia
How to Divert Water Runoff Away from Your House - WikiHow
How To Install a French Drain - This Old House
How to Install a French Drain - WikiHow
How to Install a French Drain System in Your Yard - WikiHow