Channel Drain: Explained

Overview

Channel drainage is a is a linear drainage system that is used to collect and transport water from a surface that is impermeable or where a faster drainage option is required. They’re often installed in areas such as: driveways, car parks, pedestrianized areas and patios where fast drainage is vital. 

The drains are like guttering in principle. Channels of split pipe are placed at the lowest point in the area where water will naturally flow and then covered by a grating or slot where water can seep through but allow a workable surface for cars, bikes or pedestrians to continue passing over. This collected water then gets carried by gravity to an outlet which is then deposited into a variety of further drainage solutions, these include: soakaway systems, storm drainage systems or rainwater harvesters. 

While ‘channel drain’ is its technical term, they are often referred to by a leading brand, ACO. For some, the terms are interchangeable but there are many different brands on the market offering similar products. 

Method

Rainwater running across a paved surface will generally follow the fall of the surface. A channel drain is positioned across this flow so that water reaches the channel rather than collecting on the paving.

The position and level of the drain are important. If the surrounding surface does not fall towards the channel, water can remain on the surface instead of reaching the drain.

Once water enters the channel, it travels along the channel body towards an outlet and is discharged into the site's drainage system.

Components 

The exact components depend on the system and manufacturer, but a typical installation will include the following.

Drainage Channel

The channel body sits below the finished surface and provides the route for collected water to travel towards the outlet.

Grating or Cover

The grating is the visible part of a traditional channel drain. It allows surface water into the channel while providing a suitable surface for pedestrians and vehicles to cross.

Slot drains use a narrow opening instead of a conventional removable grating.

End Caps

End caps close the ends of a channel run. Depending on the system, an end cap may also incorporate an outlet connection.

Outlet or Trash Box

The outlet provides the connection between the channel and the underground drainage pipework.

Some systems use a trash or silt box at the outlet. This provides a place for leaves, grit and other sediment to settle before the water enters the pipe. Where one is installed, it needs to be inspected and emptied periodically.

Drainage Pipe

Pipework connected to the outlet carries the collected water away from the channel. Depending on the site, the final discharge may be to a surface water sewer, soakaway or attenuation system.

Does a Channel Drain Need a Fall?

Not necessarily - The paved surface should be formed so that water runs towards the channel, but the channel itself does not always need to have a continuous fall along its length. Some systems are designed to operate with a level channel, with water collecting at an outlet or sump. A slight fall along the channel can help water move through the system and may reduce sediment settling, but this is subject to site conditions and drainage designs.

Choosing a Channel Drain

For a domestic driveway or patio, the requirements are very different from those of a distribution centre or industrial yard. Start by considering where the water is coming from, how much surface area needs to drain, what will cross the channel and where the collected water can be discharged.

From there, the channel size, grate, load class and outlet arrangement can be selected to suit the installation.

To understand the loading class need in your channel drainage system, read our article explaining the different classes, here.

Explore our range of domestic channel drains here.