How To Install A Trench Drainage System

Grating of drainage system

Are you looking for an easy way to keep excess water away from your home’s driveway or walkway? Are you considering a trench drainage system but aren’t sure how to proceed? If so, then you’ve come to the right place! This blog post will walk you through all the steps of how to install a trench drainage system, as well as how to calculate the trench depth based on load class. By the end of this article, you should feel confident about tackling this project on your own.

If you’re not sure if a trench drain is the proper drainage system for your situation, consult with a professional about an irrigation system installation or read our how-to guides on alternative drainage systems, such as French drainage systems and in-ground drainage systems in general.

How To Install A Trench Drainage System

Installing a trench drainage system in your yard may sound like a daunting task, but it doesn’t have to be. With the right tools, materials, and time, you can learn how to install a trench drainage system on your own. This guide will provide you with all of the necessary steps needed for installing a successful drainage system in your home. 

Time: A little over a day (includes dry time for concrete)

Complexity: Intermediate

Cost: Approximately $150 per linear foot


  • Spade (or other trench digger tool)
  • Safety gear (gloves, eye protection, etc.)
  • Marking paint
  • Hammer
  • Caulking gun
  • Level
  • Tamper
  • Concrete vibrator


  • High-density polyethylene (HDPE) or fiber-reinforced concrete (FRC) trench drainage system
  • Rebar
  • Caulk
  • Concrete
  • Catch basin (optional)

What Is A Trench Drain?

A trench drain is an effective and relatively inexpensive way of controlling the flow of water on a surface. It typically consists of a channeled grating that is embedded into the ground, lined with sand or gravel, sealed in concrete, and outfitted with a grate or cap to add extra protection against clogs and flooding. Most trench drains use gravity to move the water, but there are some systems that incorporate a sump pump to solve drainage issues. Installing a trench drainage system is a fairly simple process as long as it is done correctly. 

Plan Your Trench Drainage System Installation

The first step is to plan out what type of drainage system you need. This includes determining the size of the trench that needs to be dug, as well as any additional materials or tools needed. You’ll also need to consider the load class and trench depth based on the amount of water that will flow through it (more on that in a little bit). Once you have an idea of what type of system you are planning to install, you can outline where the trench will go with marking paint.

1.Dig The Trench

The depth and width of your trench should be based on the load class (load classes are technical requirements set by building codes). The dimensions of your trench will also depend on how much water you need to drain away and how you plan to hook up the system when it’s finished. 

Measure out how far down below ground level you need to dig and how wide it needs to be, making any adjustments based on local regulations. Once you have calculated how deep and how wide your trench should be, you can begin dismantling the turf layer by layer. 

It’s important to shovel out debris as you go along and ensure that the sides of your drain remain relatively level. After digging, double-check measurements to ensure that it has been done adequately and it’s ready for pre-assembly setup. Digging it by hand can be labor-intensive, so consider investing in a trencher for larger jobs–just make sure you know how to operate them properly for safety. 

Trench Depth Based On Load Class

Long earthen trench

Below is a table with the excavation depths based on load class capacity. The trench should have a minimum of 4 inches all around, no matter what load class you are dealing with.

ClassMinimum Width On Each SideMinimum Depth Below
A – 15 kN4 inches4 inches
B – 125 kN4 inches4 inches
C – 250 kN6 inches6 inches
D – 400 kN6 inches8 inches
E – 600 kN8 inches8 inches
F – >600 kN12 inches12 inches

Note: 1kN (kilo Newtons) is equal to about 100 kilograms or 220 pounds. If you are unsure what load class is required for your trench drainage system, you should consult with a professional contractor.

2.Add A Layer Of Gravel

Once you’ve dug out the trench, add a 1-inch layer of gravel along its bottom for extra stability and drainage. Compact the gravel with your tamper to create a solid base. Use a level to ensure you have the correct grading for the slope at the bottom of the trench based on the specifications for your trench drainage system.

3.Prepare The Catch Basin (Optional)

Note: You can skip this step if you are directing the water runoff from your trench drainage system to an alternative outlet.

Excavate a hole for your catch basin–the container that will collect all of the water that flows into it through your trench drainage system. Place the catch basin in the hole and make sure it has a correctly sized hole to connect to your trench drainage system. 

4.Lay Out The Trench Drain System Pieces

Lay out all the pieces from the trench drain system next to the trench you just dug. Begin with the outlet pieces and lay them next to the lowest point of the trench. This is a good time to verify that the trench you dug is the correct depth and length for the system you purchased.

5.Connect The Trench Drain Pieces

Note: There are many different trench drain systems available, so you’ll want to carefully follow the specific manufacturer’s instructions for this step.

Start assembling the pieces of your trench drainage system together and placing them in the trench. It may be helpful to use a string line to ensure you are maintaining the correct slope.

Some trench drainage systems require you to seal the joints with caulk. If that is the case for the system you have, use the caulking gun to caulk all the joints to ensure a watertight seal. You may need to wait for the caulk to dry before proceeding to the next step.

Most trench drainage systems require you to use rebar to secure the system in place before the concrete is added. Place the rebar into the appropriate holes or slots in the trench drainage system and then hammer the rebar at least 6 inches into the ground.

6.Backfill Trench With Concrete

Before backfilling the trench with concrete, cover the top of the channel drain system and any outlet holes with cardboard and tape to ensure that no concrete gets inside the trench drainage system. (Some systems may include custom-made covers for just this purpose.)

Pour equal amounts of concrete on either side of the trench drainage system. Use the concrete vibrator to eliminate any voids in the concrete. Smooth the surface of the concrete and allow it to fully cure. Depending on the type of concrete you are using, this step could take 24 hours or more.

7.Finishing Touches

Trench drain gray with steel purification grate

After the concrete has fully dried, you can remove the cardboard or other material that you used to prevent concrete from entering the trench drainage system. Then insert the drain cover grates into the top of the trench drainage system.

Finally, test your trench drain installation by filling the trench with water and making sure that your water flows in the right direction without any problems. If the water flows in the right direction and drains through the outlet–congratulations! You have successfully installed a trench drainage system. If the water doesn’t appear to be draining correctly, you may need to consult with a professional drainage expert.

HDPE vs FRC Trench Drainage Systems

HDPE and FRC simply refer to the material that the trench drainage system is made out of. HDPE stands for high-density polyethylene, a special type of plastic that can withstand the pressure that a trench drainage system will be subjected to.

FRC stands for fiber-reinforced concrete, another type of material that is well-suited for trench drainage systems. The most important distinction between these two materials is that FRC is easier to fracture or break than HDPE, so it should be handled with more care. Otherwise, the installation process for HDPE and FRC trench drain systems is essentially the same.

Simmons Landscape & Irrigation Are The Drainage Experts

Installing a trench drainage system is an effective way to divert surface water away from your property and protect it from flooding or other damage caused by excess moisture buildup. By following this step-by-step guide, you’ll be able to get started on setting up a reliable drainage system.

However, it’s important to remember that while this article provides a good overview of installation methods and techniques, it’s always best practice to consult with local experts when making decisions related to construction projects like this one–to ensure compliance with building codes in your area and optimal results once complete. If you’d like help solving a drainage issue with your property, give us a call or fill out our contact form today. We’ll be happy to answer any questions you have and help you get started on the path to a well-drained property.