Channel drains: What Are They and What You NEED To Know

Thinking of installing a channel drain or have a question about your existing channel drain?  If you do, then check out the below article which covers everything to do with channel drains.

Metal channel grates close up
Example of metal channel drains

What are channel drains and how do they work?

Channel drains, or often known as trench drains, are the ideal solution to collect and effectively disperse rainwater runoff from the ground.  

Once collected the rainwater then flows from the channel drain into some type of stormwater drainage pit, whether this being an onsite drainage method such as a soakwell or an offsite drainage method such as your neighbourhood’s drainage network.

Where can I use a channel drain and what are the benefits?

Common areas people install channel drains include:

  • Driveways and footpaths
  • Patios and backyard areas
  • Around pool decks

Benefits of channel drains include:

  • Controlling the direction of rainwater runoff away from areas that you need to keep dry such as garages or patios;
  • Reducing the chance of flooding in areas where water can not escape quickly, such as patios or confined backyards;
  • Reduces the chance of erosion to your surrounding garden beds or lawn areas; and
  • If maintained well they are an effective solution long term.

Other names for channel drains

Although commonly known as a channel drains, they are also called;

  • Trench drains
  • Driveway drains or channels
  • Patio or paving drains

What types of channel drains are there?

There are a number of different channel drains available on the market with the main differences being;

  • Size (e.g. the capacity the drain can handle)
  • The material it’s made out of (Polypropylene, plastic or concrete)
  • The type of grate it has (PVC, stainless steel etc)
  • Load capacity (How much weight it can handle)  
PVC channel drains
Polypropylene channel drains
Different types of channel drains with metal grates
Different types of drains with metal grates

What factors do I need to consider when choosing a channel drain?

When selecting a channel drain you want to ensure two main things, one is that it has the capacity to handle the expected rainfall and the other is it can take the expected load.

1. The capacity of the channel drain

When it comes to ensuring the channel drain can handle it’s important to read the capacity specifications of the channel with an understanding of the intensity of the rainfall in your area.

I often refer to this website for assisting with such calculations:
https://www.roof-gutter-design.com.au/ochan/open-channel.php

Note, in addition to the capacity of the channel the size of the outlet and pipe used also impacts the capacity or more important the ability for the water to flow out of the drain fast.  Therefore, always ensure you’re using the recommended size of outlet pipes too.

2. Load rating

When it comes to load, you need to ensure that the channel drain is suitable for the load it can take under pressure before the drain or the grate begins to either crack or buckle.

Usually, grates have a class rating such as the following:

  • Class A (Pedestrians & bikes)
  • Class B (Cars & light trucks)
  • Class C (Heavy trucks & tractors)

However, this may not be shown on the specifications.  If this is the case then look in the specifications for info such as “Load capacity” or “Recommended function” which will tell you the load or what the grate is suited for.

What is the best channel drain?

When it comes to channel drains, based on my experience, I much prefer the channel drains that have metal-based grates as time and time again I’ve seen plastic of PVC-based grates warp and lift out of channels.

Therefore, if you can afford it I’d recommend going for a channel with a metal grate and ideally a grate that is made out of galvanised steel so it doesn’t rust.

How much do channel drains cost?

3m lengths of channel drains
Example of 3m lengths of channel drains at Bunnings

In Australia, channel drains are usually sold in 1m lengths that are clicked together to reach your desired length, or if required you can buy 3m lengths.  Depending on the type of channel you buy each metre length will vary from as low as $50 up to $200.

In addition to this, you then have to buy end caps and stormwater pipe connections to run from your channel drain to your soakwell.

Where can you buy channel drains in Australia?

There are a number of outlets that sell channel drains – a few recommendations are listed below:

Final thoughts

Hopefully, the above information helped with answering any questions you may have regarding channel drains.  If you’re ready to install your channel drain then check out my step by step guide here, or for further information on stormwater drainage check out the related links below.

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