recent Post

How To Install Drainage Pipes Behind Retaining Walls

Retaining walls can transform your property, offering both visual appeal and practicality. Whether you’re looking to prevent erosion or create a level area on sloping land, careful construction is essential for success, especially regarding drainage. Investing in the correct type of drainage outlets and taking the time to install your build ensures your retaining wall lasts through all kinds of changing weather conditions for years to come.

With a reliable drainage system in place, you protect your property from potential water damage while providing an efficient way to maintain soil balance. It also helps prevent dangerous contaminants like wastewater and mud sediment from washing away with surface runoff. Installing proper drainage preserves both structural integrity and health safety around the area.

As weather patterns become increasingly unpredictable, adequate drainage is more important than ever in building design. Let’s explore the importance of drainage pipes and how to install a retaining wall drainage pipe system.

Why Is Drainage Important?

Without a well-planned system, you risk flooding and subsequent mould or structural damage to your property. With so many extreme storms now taking place worldwide due to climate changes, an efficient drainage solution that can withstand sudden downpours has never been more important for protecting what matters most.

A retained water build-up behind the wall can cause serious movement or, if bad enough, could even blast apart blocks from its construction foundation – that’s how much of a problem poor drainage becomes. When building one yourself, ensure you take all steps needed when planning out design preparations. This way, your retaining wall should last through many years regardless of what mother nature throws at it.

Generally, retaining walls are built on slopes, meaning the ground slopes down towards the top of the wall. As water seeps into the topsoil, it needs somewhere to go, which is why you use aggregate, such as stones behind the wall, to encourage water to flow more freely. However, once it reaches the base of your wall, it can build up and cause catastrophic damage.

This is why drainage matters, particularly behind retaining walls. Once you erect the wall, the ship has effectively sailed because it’s challenging to retrofit a drainage system. So, when planning your retaining wall, ensure that drainage is front and centre of your mind.

When Do You A Retaining Wall Drain Outlet?

Even if you haven’t thought about laying drainage pipes, you’re probably familiar with the practice of using aggregate, such as stones, behind your retaining wall. It’s part of the drainage system too, and we use stones and rocks instead of soil because the water can move more freely over stones than it can through the soil.

Some might suggest that certain retaining walls don’t need any additional drainage infrastructure besides the aggregate. We could list a range of occasions where you may not need drainage pipes, such as walls under 1.2 metres high or if the wall is made from timber blocks instead of cinder blocks.

But the reality is, installing drainage pipes takes minimal effort in the scheme of things. So, consider installing drainage pipes if you’re putting all that time and money into constructing a wall. The materials are inexpensive, and the process is much easier than many think.

Things to Consider Before Installing Drainage Pipes

Installing a retaining wall drain outlet may seem simple and easy, but there are some things you need to consider for effective installation. Let’s look at a few key points.

Type of pipe

Choosing the right kind of pipe helps a lot. Drainage pipes are necessary for protecting the ecosystem around you. A suitable, high-quality pipe for your retaining wall will protect your surroundings from flooding and erosion while also safeguarding the environment. DALLCON provides great protection with the help of reinforced concrete pipes. Let us know if you require any standard or custom-made precast products for your project.

Nature of soil

Consider the nature of the soil before installing pipes — soil density helps you know which place is most suited for drainage pipe installation. That’s because excess water can erode and damage the soil. Installing in areas with weaker soil structures will undoubtedly result in quicker degradation and require high maintenance.

Water accumulation

To design a drainage system that suits your needs, it’s crucial to consider the nature of how the water collects in your area. Is excess water due to seasonal or daily rainfall? Could there be a defective pipe causing water accumulation? Careful observation and study can help you determine what strategies should be applied for effective drainage, not only in the short run but for many years down the line.

Type of drainage system

From small side drains to large drainage pipes, the layout of your water collection system must be carefully chosen based on topography and land size. In spaces that require extra attention, a combination of styles may need to be implemented for optimal efficiency in eliminating excess moisture.

Expert guidance

To ensure a long-lasting solution, make sure to get expert advice and guidance in choosing and installing your retaining wall block drain. A trained professional can make all the difference in determining an effective layout that protects against water build-up while preserving its beautiful surroundings. For best results, seek advice from those with industry experience, such as DALLCON, before making any major decisions.

How to Install Drainage Behind A Retaining Wall

Make sure to plan your drainage options carefully before you get too far into the wall’s construction. Remember that laying drainage pipes isn’t your only step – it is just one part of the entire drainage system. Let’s look at a step-by-step guide on installing drainage behind your retaining walls.

Lay your first blocks

Since this article is about drainage, we won’t go into detail about preparing the ground, as you have hopefully already researched and done this correctly. Hence, the first step is to lay the first row of your wall blocks. You don’t need to do anything else except get those blocks where you want them, and then you can start preparing your drainage pipes.

This step should also include laying at least 10-20mm of clean drainage aggregate behind the wall because your pipe will lay directly on that.

Install the drainage pipe

This is the most vital step, and it’s not a matter of just getting any old pipe and placing it behind the wall. You’ll need a perforated agricultural drainpipe. These have small holes all over them, allowing water to seep through. Choose carefully because some pipes only have holes on one side. For best results, the holes should be all around the pipe.

While not absolutely necessary, it’s also recommended that the pipe has a geotextile sock around it. It basically works as a filter, allowing water to flow into the pipe, not soil and silt. This is important because a build-up of soil or other objects in your pipe will render the pipe ineffective.

The pipe is laid directly behind the wall and should have at least a 1% fall away, sloping towards your outlets. Speaking of outlets, you should have water outlets every 20 metres along the wall and at each end. You’ll need a T-connector to achieve this and suitable gaps in the wall itself. So, now is an excellent time to consider where those outlets will go.

Drainage outlets

While you can do this at the very end, installing drainage outlets is probably easier before the entire wall is constructed. There are a few different options for drainage outlets, with the most common being to have outlet pipes through the front of the wall. This is perfect for longer walls because having an outlet at each end won’t be sufficient.

Use a concrete saw to cut a hole in the blocks, just enough for a piece of pipe to fit through. You’ll need a T-connector to join these outlets to the main drainage pipe, which is another reason it makes sense to do this step now rather than later.

This method works well if the ground in front of the wall is flat. However, if there is a sloping surface in front of the wall, you can install drainage outlets that run under the wall. Either way, you’ll want drainage pipes at each end, too. Regardless of your choice, always consider using a grate on the end of pipes to stop rodents and other creatures from nesting in your pipes.

Backfill correctly

With your drainage pipes installed, you can then build the rest of your wall and add the backfill aggregate. Refer to our previous information about using stones and aggregate material rather than soil. If using aggregate, it should be at least 10-20mm. Alternatively, a better option is river stones or coarse crushed rock.

Use geofabric

Once you’ve finished backfilling your retaining wall, it’s a good idea to install geofabric on top. The fabric is much like the sock around your drainpipe. It acts as a filter, which stops sand, soil and other fines from seeping into the backfill.

Lay it between the top of your backfill stones and under any topsoil you add. As an extra precaution, you can add geofabric material to the entire back of the wall blocks to prevent soil ingress, but this isn’t a requirement and may depend on your particular site.

Ultimately, putting the time and effort into drainage gives your retaining wall the best chance of being effective and looking great for many years to come.

The Best Retaining Wall Drainage Pipe Solutions in NSW

A proper drainage system ensures your place is safe from any form of water blockage while also preserving the beauty of your surroundings. DALLCON provides tailored solutions to meet any drainage pipe, culvert, or sewer system challenge. Whether you need large quantities of standard sizes or even custom solutions delivered right to your doorstep within strict deadlines, we’re here to help!

Our team of specialists are happy to take the burden off your hands and handle all aspects of selection, delivery, and installation if required. Contact 1300 325 526 or email us at for more information and guidance on retaining wall drainage pipe solutions in NSW.





We supply custom made things ranging from custom panels to other stuff