Rainwater Downpipes: What Are They and How Do They Work?

In Australia, a downpipe is a pipe that connects to your roof gutters, allowing rainwater to be funneled off to a preferred location.  Usually, downpipes are connected to, or flow into drainage pipes that lead to a soakwell a couple of metres away from your property.

Temporary downpipe shoe

Why do I need downpipes?

Downpipes are important as they allow to control the flow of water coming from your roof which you can then direct to a soakwell or soakaway.  This is important as it avoids rain running off your roof and potentially pooling or collecting around the foundations of your house.

What are downpipes made of?

In Australia, downpipes are usually made of steel (zincalume) and come in a number of different sizes and colours.

For those that are looking for something different, you can also get stainless steel downpipes such as in the photo below:

Stainless steel downpipe with T bracket
Example of a stainless steel downpipe

In addition to steel downpipes, you can also get PVC downpipes which are common in countries such as Europe though not as popular in Australia due to the hotter climates.

What sizes do downpipes come in?

Rainwater downpipes come in all different sizes within Australia, however below is a list of the most common sizes.

Rectangular downpipe sizes

  • 45 x 95mm
  • 50 x 100mm
  • 75 x 100mm
  • 125 x 100mm

Square downpipe sizes

  • 75 x 75mm
  • 100 x 100mm
  • 150 x 150mm (used for commercial buildings)

Circle downpipe sizes

  • 50, 65, 75, 90, 100, 125 & 150mm

What lengths do downpipes come in?

Most roof plumbing supply companies sell the above downpipes in either 1.8m or 2.4m lengths, however, if need be, some roof plumbing companies can custom make downpipes to a length to suit.

Generally, you’ll find that 1.8m downpipe lengths are used on single-storey houses (two per downpipe), and the 2.4m downpipes are used on two-storey houses.

What colours do downpipes come in?

Downpipe colourbond colours
Common colourbond colours that downpipes are made in

Downpipes within Australia come in a number of different colours.  As they are made out of zincalume the stock standard colour of a normal zincalume downpipe is a shiny grey colour. 

If you opt for a colourbond colour then common colourbond colours include:

  • Surfmist
  • Windspray
  • Ironstone
  • Deep ocean
  • Sandbark
  • Evening haze
  • Pale eucalypt
  • Wilderness
  • Cottage green
  • Shale grey
  • Classic cream
  • Paperbark
  • Headland
  • Manor red
  • Jasper
  • Dune
  • Bushland
  • Woodland grey
  • Monument
  • Loft

How are downpipes fixed to the gutter?

A zinc downpipe pop for gutters
Example of a 95x45mm rectangular steel pop available at Bunnings

Downpipes are fixed to gutters via a downpipe pop. This downpipe pop is installed into the base of the gutter and the downpipe is then fixed to the wall and riveted to the downpipe pop.

Usually, you’ll find there will be one rivet in the front of the downpipe through to the pop or sometimes the rivets are in the side of the downpipe into the pop.

How are downpipes fixed to the wall?

Downpipes are fixed to the wall using metal straps.  Depending on the shape of the downpipe you are installing, the straps will vary in size and shape.

Rectangle or square downpipes

Flat metal downpipe clips for sale at Bunnings
Example of steel 100x50mm rectangular brackets

For rectangular or square downpipes, the straps will come in a flat format which you then bend to suit.  Once bent to the shape of the downpipe you then fix the downpipe to the wall using the bracket.

Round downpipes

Zinc downpipe clips for round 75mm pipe
Example of your stand steel strapes at Bunnings

For round downpipes, the metal straps will come in a circular shape which you can slide over the downpipe and fix to the wall or there are also other circle brackets that stand off the wall via a T shape bracket.

Circle downpipes with metal clips onto post
Above is an example of how such clips are used to fix circle downpipes to a veranda pillar

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