How to install French drain pipe and fittings for easy Roto-Rooter cleaning in the future

Please first read Steps 1 to 4 of our Drainage Guide

This page provides information on:

The secret to good French drain system is keeping roots, soil, and debris out of the gravel and pipes. By wrapping the gravel in permeable landscape cloth and the piping in fabric drain pipe sleeve you minimize the soil and clay silt that can destroy water flow.

But roots are tricky things that will wiggle their way through every gap in your protection until they finally find their way into the drainage pipe. Once there they will grow and expand to collect as much water as they can. When they expand too much the roots will begin to block water flow through the French drain pipe.

Debris like leaves, twigs, nests, mulch, and even deceased animals are another cause of blocked French drain pipes. Drainage systems that are connected to the house downspouts or that include surface drains are especially prone to this problem.

So how do we deal with plugged pipes in a French drain? Well you could dig all the piping up every decade or so to clean it out (no thank you), or you could build your drainage system so that a plumbing company with a sewer snake - like Roto-Rooter - can quickly, easily, and safely clean you pipes anytime they need it. A sewer snake is a whirling blade on the end of a semi-flexible cable that pushed through the pipe to cut and chew through roots, soil, or debris that is blocking the pipe.

To do this you must have the right kind of pipe, the right kind of fittings, and above ground locations they can access.

Drain Pipe and Tile - If you want to be able to run a sewer snake through your French drain you MUST use rigid PVC drainage pipe (the modern drain tile).
  * Do not use the flexible corrugated perforated plastic pipe as it is too soft and the whirling blades will cut it to bits and destroy your system.

Pipe Fittings

There are many fittings available for 4" rigid PVC pipe. We are basically interested in tees, wyes, elbows, caps, and maybe reducers. As you select fittings keep in mind that you want to pick fittings that a whirling blade on the end of a semi-flexible cable can easily travel and turn through. Often a sewer snake can not make the turn in a close elbow or a bull nose tee. Also note that a sewer snake traveling across the top bar of a tee or wye fitting will skip right past the opening for the upright of the tee or wye, but when traveling through the upright it will always follow the curve in a sanitary tee or wye.
* See the Fittings drawings...

Elbow and Tee fittings for drainage pipe

 

Drainage Pipe Installation

Planning your drainage pipe installation for easy cleaning by a Roto-Rooter type machine is mostly a matter of choosing fittings to direct the sewer snake to the far end of the French drain. As in a home where a sewer snake is always ran from the toilet pipe to the sewer, snaking out a French drain is done from the collection point of the system through to the outlet.

In the example below we show a simple TEE arrangement of piping that will collect and drain excess rainwater successfully, but can not be completely cleaned with a sewer snake. Because a simple tee fitting is used in this example, a sewer snake that enters from the surface drain will skip right past the opening to the French drain (and eventually come out the downspout connection), and vice-versa when inserting the sewer snake in through the downspout connection.
* See the diagram below, or to the right...

 

Poor pipe layout for cleaning a drainage system

 

 

Better layout for easy cleaning...

But look at the following example to see what happens when we replace the simple tee fitting with a collection of fittings that steer and direct the sewer snake into the French drain.

Inserting the sewer snake into either the surface drain OR the downspout connection results in it easily and reliably entering the French drain.

This example is typical of the type of pipe connections you will want to use in your French drain system.
* See the diagram below, or to the right...

 

Good pipe layout for cleaning a drainage system

Visit our other Drainage Guide pages and our "Just Tooling Around" blog

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Page last modified on 2017-10-07