The Definitive Guide to Trench Drain Systems 101


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What is a Trench Drain?


A trench drain is a linear drainage application used to catch, collect and convey water from a starting location to and an outlet or catch basin.

These linear drains are made up of primarily channels, end caps, end outlets, grates, catch basins and some other installation accessories.

Channel materials include: Fiber Reinforced Concrete, Polymer Concrete, Stainless Steel and HDPE.

Grate materials include: Ductile Iron, Cast Iron, Galvinized Steel and Polymer.

Technical specifications can be viewed here.



What Are Trench Drain Systems?


Trench drain systems are linear surface drainage applications used to remove water from places where it tends to pool. These drains can be installed inside or outside your home or business.

Common interior locations for trench drains include showers, pools, and garages. Common exterior locations include:

Trench drains are also important features in industries, agriculture, and public planning. On public roads, trench drains remove water after heavy rains. In industrial facilities and other job sites, trench drains remove water and other liquid waste produced by machines. In facilities that care for animals, trench drains can keep kennels or stalls free from waste.





How Do Trench Drain Systems Work?


In all cases, linear drains rely on gravity to carry water away from locations where it pools. Thus, as you work with an installer to design your trench drain system, you'll need to discuss run, slope, and width




Run refers to the length of your drainage system, which should extend across the area where water pools.

Across that length, or run, your trench will also need to gradually slope downward toward the disposal area. Depending on the type of system you choose and where you install it, installers may:

  • Hand-form this slope on-site
  • Construct it from pre-sloped sections
  • Rely on the natural slope of ground that is already pitched





If you are installing a linear drain system in an area that is already pitched, you may choose a neutral channel trench train. Neutral channels may also be necessary when depth constraints prevent you from installing deeper channels.


HDPE trench drain channels have anchors for rebar to prevent floating


When they can be installed in flat areas, however, pre-sloped trench drains have certain advantages. While neutral channels will still drain most flat areas, sloped drains increase velocity. They also prevent the buildup of debris that can lead to blockages.

Finally, the effectiveness of a trench drainage system depends on its width. Common widths are 5", 6", 8", and 12". Wider channels increase flow rates and can handle more water. Thus, channel widths of 5-8" are generally sufficient for moderate pooling. Twelve-inch channels are better suited for areas with significant drainage issues.



Intersecting T connection for a pre sloped brewery drain system



Ultimately, the goal of a trench drain is to remove water to a disposal site. Therefore, you'll also need to consider the width and placement of the outlet pipe to promote proper outflow.

As you select your linear drain materials, an expert can help you determine the options that best serve your needs.

Benefits of Trench Drain Systems


Drainage systems protect and enhance your property in a variety of ways.

First, they protect your property against water damage. When water pools outside, it can damage your lawn. If it pools regularly, it can also seep into the foundation of your house and cause interior and structural damage.

On potentially slippery surfaces, like pool decks and patios, trench drains also increase safety. Evacuating water quickly reduces slipping hazards. This is true—and important—in all weather. When water pools in the winter, it freezes, producing dangerously icy surfaces.

Paved surfaces around your property also tend to last longer when they utilize trench drains. These include exterior surfaces, like driveways and sidewalks, and interior surfaces, like basement and garage floors. Just as pooled water can seep into and weaken the structure of your house, pooled water can seep into and weaken paved surfaces. Trench drains prevent this pooling.

Safety improvements from trench trains also include sanitation considerations. Pooling water can produce property damage and injury hazards. However, stagnant water is also a breeding ground for mosquitos, bacteria, viruses, and parasites. Installing a trench drain system can help to ensure that you're not sharing your home with these health hazards.

Although you don't see them and, therefore, likely take them for granted, trench drains, finally, protect you on public roads. Following heavy rains, water pools on highways, roads, and bridges. Trench drains remove this water and reduce the risk of hydroplaning.



Trench Drain Terminology and Alternatives


As you explore trench drain options, you may find certain terms used interchangeably. These include "trench drain," "channel drain," and "line drain." Each of these terms describes a drain system that removes water via a trough—or open trench—with removable grates.

French drains and slot drains are sometimes confused with trench drains. While they have similar purposes, their structures are distinct.

french drain structure buries a perforated pipe, surrounded by gravel, in a channel. Like a trench drain, this structure collects and removes water from an area where it pools.

Slot drains likewise evacuate pooled water. However, they utilize slots in the pavement that are connected to underground pipes. Unlike trench drains, slot drains do not have removable grates.

Other options for surface water removal are the catch basin drain and the swale drain.

Catch basin drains are similar to linear drains in their use of removable grates. However, catch basin drain grates are generally square or round. As such, they cover a much smaller surface area than the linear trench drain.

Catch basin drains also require deeper excavation to install. Furthermore, they tend to be more difficult to maintain. While trench drain pipes are relatively accessible, catch basin drain pipes are not. This problem is compounded by the fact that catch basin drains are more susceptible to blockages. For this reason, catch basins tend to be less effective at removing pooled water.





Finally, swale basin drains are among the simplest drainage options. They consist of a wide, shallow ditch lined with grass, rocks, or other ground cover. Like linear drains, these ditches gather water and carry it away. However, swale drains can be overwhelmed by runoff from large storms. They also are less effective at preventing soil contamination from bacteria and chemicals in runoff.


What Are My Trench Drain Options?


Once you've decided that a trench drain best serves your needs, you need to find the best trench drain for you.

Linear drains come in different materials for different applications. Two main types include the concrete trench drain and the high-density polyethylene (HDPE), or polymer, trench drain.


Concrete Trench Drains


For areas that endure significant and sustained weight loads, including vehicular traffic, concrete trench drains may be a good option. Concrete drains can be cast in place or precast.


Cast-in-Place Concrete Trench Drain Systems


Cast-in-place trench drain systems are the original trench drain. However, they are also among the most labor-intensive and expensive.

Like any trench drain system, building a concrete trench drain on-site requires, first, digging a trench. Once the trench is excavated, installers line it with a wood frame before casting it with concrete. This process is time-consuming, which makes labor costs significant.

Because these drains are hand-formed, they can also exhibit variations in the slope. This can affect drainage since trench drain systems rely on gravity to evacuate pooled water. The wider pipes in these systems may also allow debris to gather, which can, in turn, slow drainage.

Finally, concrete is a porous material. Thus, it absorbs water. This means that concrete trench drains may not be as effective at keeping contaminants from the soil. They may also eventually need repair or adjustments as the concrete erodes. Patching can be difficult and time-consuming.


Pre cast Concrete Trench Drains


Pre cast concrete trench drains use a similar structure to cast-in-place systems. However, the concrete trenches in these systems are made in a factory and transported to the installation site in sections. These pre-cast pieces cut down on installation time and labor costs, but manufacturing costs can be higher. Because they are not hand-formed, they also offer a more uniform slope.

Like cast-in-place concrete trench drains, pre cast systems are able to bear significant and sustained weight. This is why trench drains in public roads use concrete materials. Forklift rated trench drains are likewise able to bear loads imposed by heavy construction machinery.

Also like cast-in-place systems, though, pre cast concrete drains can allow water to seep into the soil. They are likewise subject to erosion and may need to be repaired or adjusted over time.

However, most heavy duty concrete trench drains use fiber-reinforced concrete. In this construction, fibers of steel, glass, and other synthetic and natural materials strengthen the concrete. This prevents cracking, crumbling, breaking, shattering, and erosion. It also reduces permeability, which prevents soil contamination. View technical specifications here.





  1. Catalog
  2. Installation Guide



High-Density Polyethylene (HDPE) Trench Drains


Like pre cast concrete trench drains, HDPE, or polymer, trench drain systems are manufactured in a factory and transported to the installation site in pieces. The pipes used in HDPE trench drains are constructed from lightweight but highly durable polymers.

This lightweight material means that installation is easier and faster. It also tends to be more cost-effective.

Importantly, if you intend to install a polymer linear drain on a surface that bears vehicular weight, you'll need to reinforce it with a concrete encasement.

Polymer piping with a concrete encasement combines the superior weight-bearing properties of concrete with the impermeability of plastic.

Polymer piping also doesn't absorb water. This means the pipes themselves are durable. It means, further, that water or waste containing bacteria, chemicals, and other toxins doesn't reach the soil. Polymer trench drains are, therefore, especially useful in industrial settings. View technical specifications here.






  1. Catalog
  2. Installation Guide
  3. Encasement Detail
  4. Slope Detail



Grating Materials


Whether it uses concrete or polymer piping, your new linear drain system will also require a grate covering. Grating materials include cast iron, ductile iron, galvanized steel, and stainless steel.


Cast Iron Grates


Cast iron and ductile iron are cost-effective and durable options for trench drain grating. They also offer increasingly decorative options.

Because the grate is the part of a trench drain system you'll most often see, appearance is a consideration. Raw cast iron naturally rusts. As a result, it develops a reddish hue over time. Eventually, this rust can bleed and discolor the surrounding concrete as well.

Coating a cast iron grate with powder or epoxy paint can prevent this rust, at least for a time. When aesthetics are a concern, powder coating and epoxy paint can also help you match the grate to the surrounding surface.

Of the two materials, epoxy paint tends to be more durable. However, research continues to make advances in the durability and environmental-friendliness of both coatings. Still, any color modifications are subject to wear away over time. Thus, they require additional maintenance.

When the grate's ability to withstand significant weight or impact is as important as its appearance, you might consider ductile iron. Ductile iron grates combine the aesthetics of iron with the strength of steel.





Decorative ductile iron grates


Steel Grates


Stainless and galvanized steel boast the toughest properties. They are also rust-resistant, maintaining their silver appearance in most conditions.

If you choose steel grating, keep in mind that some types can still react with salt and acids in rain or pool water. Galvanized steel and some grades of stainless steel do not hold up well under prolonged exposure to saltwater. Deicing chemicals can also degrade galvanized steel. Thus, you may need to choose a different grade of steel for a grate in a shower drain than for a grate in your driveway or on your pool deck.

Many homeowners find the shiny appearance of stainless steel fits well with the sleek modern designs in their homes. It can also complement light-colored concrete and other paved exterior surfaces. Stainless steel is used in industries such as breweries, chemical processing, food and beverage and the like.

Whether galvanized or stainless, steel is more difficult to cast than other materials. Thus, grates tend to include more basic patterns of slots, bars, or holes.

As you sort through various options and considerations—from aesthetic to functional, a trench drain expert can help you select the materials that are best suited to your needs.


Polymer (Left)

Stainless Steel - ADA , Heel Proof , Perforated (Middle)

Ductile Iron - Forklift Rated , Class D (Right)


Money Invested in a Trench Drain Is Not Money Down the Drain


A linear drain system is an investment. However, it can save you money and trouble in the long run. Investing in a trench drain system can protect your property from serious and expensive water damage. It can also protect you and your family from injuries and illnesses due to slippery surfaces and stagnant water.

Choosing the right trench drain system for your needs maximizes the return on your investment. As you explore different trench drain systems, count on the experts at Swiftdrain. Contact us today with questions or to request a quote.





Material Choice and Components


As discussed, there are two major groups of trench drains. Polymer Channels and Concrete Channels. Polymer based channels can come in the form of hdpe (high density polyethylene) or fiberglass. Concrete based channels can come in the form of fiber reinforced concrete or polymer concrete. Polymer channels have anchors for rebar which prevent floating during installation. Concrete channels have articulated mechanical anchors which come pre formed in the trench drain channel which provide added stability during installation.

Drain widths are typically 4" , 5" , 6" , 8" or 12" wide. Anything larger than 12" is usually overkill. They come in varying depths, with shallow profiles, deep profiles or pre sloped systems. Pre sloped trench drains usually have a .75% or 1% external slope. Meaning, that each channel is numerically numbered and slightly deeper than the one that precedes it. For instance Channel 1 could be 4.25" to 4.75". Which would connect to Channel 2 which would be 4.75" deep to 5.25" deep.


Trench and Channel drains are primary made up of:



The Channel:





The Grate:



Cast iron grates on an hdpe channel (Left) Galvinized Steel perforated grates on a concrete channel (Right)



The End Cap / End Outlet:






Or Bottom Outlet:







Optional Catch Basin:




Most of these parts are beneath the surface and after they are installed shouldn’t be seen from or heard from if installed properly. Channels can come with attachments for re bar on the side which secure the channel to the concrete bed which will be poured as shown in the following clip.




Trench Drain Channels are long, tubular u shaped conduits.

The channel can be made of:

  • HDPE/ Fiberglass / Polymer
  • Polymer Concrete
  • Fiber Reinforced Concrete
  • Cast iron,
  • Stainless steel

Plastic derivative channels are more than sufficient for most residential applications.  One of the main things to consider when determining channel material is load bearing.

Load bearing is how much weight the drain can and is expected to hold. In most residential situations, the heaviest thing that will be going over these drains are delivery trucks, oil and gas trucks and typical “highway rated traffic”. In most instances a polymer channel should be sufficient. Higher grade materials wouldn’t add much functional or structural integrity to the system.  Polymer channels are budget friendly, last long and easy to assemble.

There are some differences between channels. As previously mentioned, some have anchors for re bar to prevent the drain from floating during installation. The Dura Slope has anchors that are pre fabricated, circular place holders for re bar. This thoughtful and measure allows the installer to fasten re bar beside the channel every section and the concrete will be poured around the re bar to prevent it from “floating” or moving during the installation process.

In lieu of re bar, other manufacturers have chosen to have articulated channel bodies so the concrete can form a natural “wet blanket” around the rivets as its poured.  These indentations allow the poured concrete to form better and also gives an added layer of foundation.



Concrete channels have vented articulated designs to conform with concrete pour


More on ASTM Standards and Ratings can be viewed here.


How to select the right drain? When selecting the right drainage system consider the following

Load bearing How much weight will the trench drain need  to bear. Load is classified into different load classes (light, medium and heavy). Choosing the appropriate load capacity is determined by the type of traffic.
Type of traffic- Pedestrians, cars, trucks, forklifts airplanes and wheel load. Pedestrians require ADA slot styles and heel proof grates so shoes don't get stuck.

Drain sizing - Depending on expected flow rates, most drains will be 4”, 6” or 8”. Drain sizing depends on flow rates, land size and how much water is expected to be drained.
Channel & Grate Selection
Choose the right channel and grate with heavy duty enhanced concrete, HDPE, cast iron, stainless steel or polymer

Site conditions play a significant role in determining channel material. Stainless steel works better in extreme temperatures with freeze and thaw cycles. Stainless steel deals well with chemicals and caustic agents. Galvinized steel does not rust. Cast iron does well for general purpose interior and exterior use cases.

Grates are chosen based on site and user requirements, load bearing, and expected water flow. Generally, 3" - 12" is a safe width to use. Grates are made in cast iron, ductile iron, stainless steel, polymer and other materials. Polymer is suitable for pedestrians. Cast iron and galvinized steel for cars, trucks, forklifts and traffic rated applications. ADA grates (American with disabilities act) and heel proof grates are a good choice for pedestrians.

Residential Drainage

Commercial Drainage

Drains are an integral part of any home. A good drainage system will keep the house free from water accumulation caused by improper slope that can result in foul smell, seepage and mold. During spells of excess rainfall many residences face the problem of water accumulation in their foundation, basements, driveways and yards. Not only does it look unsightly, it can ruin the landscape and cost a fortune to get the damage repaired.

Residential linear drains serve the purpose of removing surface water from storm water runoff and excess rainfall by diverting it effectively from areas prone to flooding. Why use Residential Linear Drains? Channel Drains are so versatile that using it for residential application is as easy as it comes. With a wide variety of sizes and patterns to choose from, trench drains are no more eye sores in an otherwise lovely landscape. Trench drains can be customized based on individual

Materials used to make trench drains are strong with high compression strength and low porosity such as cast iron, steel, polymer concrete and fiberglass. They are easy to assemble within a trench and need to be set in concrete to help attain integrity required for a good drainage system. Trench drains can be used within the house such as in the shower room, indoor garden, external kitchen and porch. Trench drains can be used outside the house for swimming pools, gardens, downspouts, barns, outhouse, driveways and sidewalks.
While drainage is commonly associated with runoff from rainfall, it is equally applicable in commercial establishments such as food processing units, chemical factories and vehicle service centers. Industries that utilize processes that require the use of cleaning agents need to have a good drainage system in place. Surface storm water runoff near commercial establishments also need to be managed in order to prevent clogging of storm water drains.

Commercial linear drains are available in a number of visually appealing decorative designs. These trench drains are eco-friendly and adhere to safety norms such as Americans with Disabilities Act (ADA). Public places such as parks, pools and water fountains utilize decorative commercial trench drains and grates that adhere to ADA for the benefit of pedestrians and tourists in order to enable them to walk over freely.

Decorative trench drains with decorative grates are also great for use near office buildings and businesses. Parking areas also require trench drains and should be installed in such a way that vehicles never run over the length of the grate. It is a good idea to install trench drains in warehouses that store goods. Excess rainwater or storm water runoff can be easily directed away from the warehouse by installing trench drains on the periphery.