How to Install FLEX-Drain

FLEX-Drain Drain Pipe Installation

Drainage Pipe Installation Overview

  • FLEX-Drain expands and contracts and fits to any shape.
  • FLEX-Drain comes in multiple length solid pipes as well as perforated and perforated with sock.
  • The FLEX-Drain Flexible T / Y allows you to tie multiple pipes together.
  • The FLEX-Drain coupler allows you to attach cut pieces of pipe to each other, and to other drainage products.

Diagnosing the Problem

  • Start by identifying the issues causing your drainage problems. 
  • In this application, we will be replacing old downspout adaptors as well as an existing french drain.
  • FLEX-Drain is perfect for tight places and curvy spaces.

Drain Pipe Installation Preparation

  • Measure the job site and downspouts and buy supplies accordingly.
  • Have Utilities marked before you dig and apply for any necessary permits.
  • Assess the ground slope and plan for where you will lead the water.
  • Be prepared with gravel (depending on application), top soil and grass seed as part of your supply list.  


  • Renting a trencher makes quick work of digging and it doesn't cost a lot of money.
  • Measure trenches from 4-12 inches deep based on your project specifications.
  • For normal installation in mild climates, 8 inches is the standard.

Basic Installation

  • Installing FLEX-Drain is the easiest part of your project.
  • Connecting downspout adaptors to downspouts is easy.
  • Expand your pipe to fit and run the pipe in your trenches.
  • Install the Flexible T Y by snapping on the coupler first. Coupler TIP: Always attach to the cut piece first.

French Drain Installation

  • The idea behind French Drains is to rid your yard of low-lying water by allowing it to seep into the ground via perforated pipe and a barrier of gravel.
  • When it's time to connect the perforated pipe with sock to other pipes, cut the sock to connect to other pipe.
  • Block the end of the French Drain by tying the extra sock in a knot.

Tight Places, Curvy Spaces

  • The ability to use FLEX-Drain in tight places or around curvy spaces makes this job simple..
  • FLEX-Drain can be installed around retaining wall, existing plants and trees or anything else that you don't want to dig up.


  • Install an end-cap to run the water out to the street, or into a gutter, for a nice clean finish.
  • Backfill the pipe with gravel where the perforated pipe has been used.
  • For basic installations, backfilling with top soil is sufficient.
  • Put some grass seed over your finished project and your yard will be good as new!


How to Install Drain Pipe Video Transcription

How To Install

We’re here in downtown Atlanta to install FLEX-Drain, a 4-inch expandable drainpipe system. FLEX-Drain expands, contracts, fits to any shape, comes in multiple sizes, and also comes in perforated and perforated with sock. We’re going to use our flexible T-Y. It expands and contracts, and this is going to allow us to tie multiple pieces of FLEX-Drain together to make the system work. We’re going to tie multiple lines all into one main line. We have our coupler, and our coupler attaches to the mail end of all of the fittings, also to cut ends to pieces of the pipe, so that when we make our connections we’re going to use this to make that seam.  Then we have our downspout adapter, it expands and contracts as well. This is going to go onto the gutter and then it connects the pipe into the system underground and lets all the water run away.  

Diagnosing the Problem

The problem we have here today, as you can see, we’ve got the downspout adapter, and then we’ve got a lot of erosion in the ground here. What we’re going to do is go ahead and cut this lip off, attach one of our downspout adapters to it, and then we’re going to bury a solid line all the way down the hill so the water stays inside the pipe and stops the erosion. The other part of the problem is we’ve got a downspout here, and you can see all the erosion here. So we’re going to bring that pipe from up top that we talked about, bring it down here, and connect it. We also have a French drain that doesn’t work anymore; it’s clogged.  So we’re going to go ahead and put our downspout adapter on here, tie our flex drain line in, remove the old french drain and put a brand new line in all the way out to the curb like it’s supposed to be done. The last application we’re going to do is perfect for FLEX-Drain. We’re going to tie into this gutter right here and you can see we have a real tight, curvy, area so we’re going to tie our tie in to this and bury a pipe and go right up around this post and bring it out on the driveway with the grate so we get a nice clean drainage area to get rid of this erosion.

Drain Pipe Installation Preparation

To prepare for your FLEX-Drain project the first thing you want to do is measure the job site out, make sure you get enough pipe and enough fittings to do the project. Also measure your downspouts; make sure you’ve got the right size opening for your downspout adapter that connects to your gutter. There are several sizes, make sure you choose the right one. You want to also make sure that all of your utilities are marked out before you dig and if there are permits required to dig in that area that you get the right permits and all the utilities are marked out. You also want to make sure you’ve got the right slope. So you make sure that the water can be sloped away from the house, and will be brought off in the right area. The last thing you want to do is make sure that you’ve got all your supplies and gravel in advance so that when you’re doing the job you’ve got everything there for it. 


For this project we went ahead and rented a trench digger. I recommend it for anybody that’s going to install the FLEX-Drain system. It makes quick work of digging, and doesn’t cost a lot of money. You want your trenches to be about 8 inches deep. You can see here when you’re done digging your trencher you will have to go back with a shovel and clean out some of the loose dirt to make sure that you don’t have any high spots.

Installing Drainage PIpe

Now comes the easiest part of the job. We’ve already connected our 3x4 downspout adapter. Now we’re going to take our FLEX-Drain solid pipe, expand it out, and put it in the ditch. We’re going to install our flexible T-Y. Keep in mind when you’re installing a flexible T-Y you will need typically one or two couplers depending on the installation. For this one we’ve got 2 male ends coming together. So, we simply snap on the coupler here, take the male end of the pipe, snap that side on, and get it into place. Now that it’s in place the next thing we’re going to do is attach a downspout adapter to a short piece of pipe. First thing take your downspout adapter, get that up and snug. Now you’re going to have to cut a piece of pipe because you’ve got just a short run. The nice thing is you don’t really need to measure because it’s FLEX-Drain, so take a piece that’s about the right size, attach the other coupler, and the tricky thing here, always attach it to the cut piece first. By taking your fingers through the back of it and pulling the pipe until you hear that click. Then you can snap on to your flexible T, snap the other end onto your downspout adapter, and expand it to fit. To finish off this part of the installation you just take your female end of your next piece of pipe, snap it on, and run it out to your ditch.

French Drain Installation

What we’re going to do here is we’re going to change from our solid pipe and use a perforated pipe. In this application we’ve decided to use a perforated pipe with a sock because there is a lot of fine soil. What we’ve done now is we’ve connected solid pipe to the downspout adapters and that’s going to solve the problem of the water run off.  They still have an area right here with low-lying water that tends to puddle up. We’re essentially going to create a French drain and tie the whole system together. We’re going to take this [FLEX-Drain] and we’re going to expand it out. Go ahead and get this in the ditch like so. Cut the sock here because what we’re going to do is now is to take another one of those flexible T-Y’s and we’re going to connect in our two downspout lines that we’ve already got pre-connected. First thing you want to do is connect your couplers to your cut pipe. Pull the pipe through with your fingers until you hear it click and it feels really good and secure. And you’re going to need 3 of them in this application because you’re going to have three pieces of cut pipe. Now you connect your T. You want to make sure your pipe is down nice & deep. What we’re going to do here, we’re going to bury this whole pipe underground. The easiest way to block the end is just to simply take your extra sock, tie it off in a knot, and bury it down underground.

Tight Places, Curvy Places

Just like on the other side of the house we have the same problem with the downspout adapter. What we’ve done, we’ve already dug our trench, put our pipe in place, connected our downspout adapter to our FLEX-Drain pipe, ran the pipe through, and around the pole, simply connected it to a grate drain right off to the end of the driveway, stopped the erosion. Simple and easy.

Finishing the Drain Pipe Installation

The last thing we have to do before back filling our pipe is to install a simple end cap to make sure that you’ve got a decent looking end. There’s lots of different ones available from several different manufacturers. Things like this one with a pop up, which we could use here. However, there’s no curb here so we’re gong to go ahead and just use a simple 4-inch PVC with an end cap. And to install this, again you need to take a coupler, install it over the male end of our pipe. And then simply snap it in the back; it’ll give you a nice, clean finish. And then you just back fill the pipe.

Our FLEX-Drain installation is complete. We’ve installed our solid drainpipe into our downspouts, removed the old, french drain, installed the brand new french drain, we back filled everything and put some starter soil down. The only thing left is to put a little bit of grass seed down. And in just a couple weeks it’ll look just like a golf course all over again.

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