The Simple Water Check That Can Improve Every Retaining Wall Project

Water around retaining walls is one of the most overlooked factors in a successful retaining wall project. Most homeowners naturally focus on the wall itself—how tall it should be, what material to use and how much it will cost. However, after inspecting hundreds of retaining walls across Brisbane, I’ve found that understanding how water moves across a property often has a bigger impact on long-term performance than the wall itself.

So, the next time Brisbane gets one of its famous downpours, don’t stay inside. Grab an umbrella, walk around your property and simply watch where the water goes.

You might learn more in ten minutes than you will from hours of studying plans.

Why Water Around Retaining Walls Matters Before Construction

One thing many homeowners don’t realise is that when we inspect a retaining wall, we’re rarely looking at a brand-new structure.

Most walls have been standing for decades.

Over that time, they’ve accumulated gardens, trees, paving, renovations, drainage changes, extensions and all the little improvements that naturally happen as people live in a home.

When I arrive on site, I don’t know exactly how the wall was originally built.

Even so, I know something has changed.

Rather than focusing only on the visible damage, my job is to understand why it’s happening.

That difference matters.

After all, repairing the symptom without addressing the cause usually means the problem will return.

Water Around Retaining Walls Doesn’t Always Start at the Wall

One of the biggest misconceptions about water around retaining walls is assuming the wet area must also be the source of the problem.

In reality, rainwater might begin on:

• Your roof
• A neighbouring property
• A driveway
• An upper garden
• A paved entertaining area

By the time it reaches the retaining wall, it may have travelled through several different parts of the property.

For that reason, experienced contractors don’t just inspect the wall.

Instead, they assess the entire site.

Viewed in context, the retaining wall is simply one part of a much larger drainage system.

Water Always Takes the Path of Least Resistance

I say this to clients all the time.

Water doesn’t care where you want it to go.

Instead, gravity determines its direction.

From there, the surrounding levels influence its path.

Ultimately, water follows the easiest route available.

One of the best examples involved a homeowner who had already spent more than $16,000 plus GST trying to solve drainage problems.

Every time heavy rain arrived, water flooded against the alfresco.

Naturally, they assumed they needed more drainage.

However, after walking the property, the real issue became obvious.

The landscape itself directed water towards the house.

Instead of recommending another expensive drainage upgrade, I suggested creating a simple surface channel that allowed water to escape naturally towards the fence line.

Sure enough, the next significant rain event proved the point.

The flooding disappeared.

More importantly, it reinforced an important lesson.

Managing water around retaining walls almost never comes down to a single fix.

Instead, it’s usually a combination of many smaller decisions working together.

You might install:

• A concrete plinth beneath the fence
• A retaining wall with an open drainage system
• Agricultural drainage behind the wall
• A dry creek bed through the garden
• Soft planting to slow surface runoff
• Strip drains where appropriate
• Concrete that falls away from the house

Individually, each improvement might solve only part of the problem.

Together, they create a property that manages water far more effectively.

Think of them as a series of gentle barriers, each helping guide water safely through the landscape rather than trying to stop it altogether.

Why a Drain Alone Won’t Solve Water Around Retaining Walls

This is probably the biggest misunderstanding I see.

A homeowner tells me,

“I’ve got a drain there, so why is it still flooding?”

The answer is usually more complicated than the drain itself.

Imagine thirty or forty square metres of water trying to find one 100 mm pipe.

That’s already asking a lot.

Now imagine the pipe sits slightly higher than the surrounding ground.

Everything around it fills with water before it even reaches the drain.

On top of that, most stormwater systems already have limits.

During severe Queensland storms, you’re often trying to push more water into a network that’s already operating at capacity.

As a result, the system simply can’t accept any more.

That’s why adding another drain isn’t always the solution.

In many cases, reshaping the land delivers a much bigger improvement than installing additional pipework.

Landscaping Plays a Big Role in Water Around Retaining Walls

At its heart, landscaping is simply shaping land.

Features such as retaining walls, garden beds, concrete paths, lawns and new paving all influence the way water moves across your property.

The best landscape designs don’t fight water.

Instead, they quietly guide it.

When they’re done well, most people never even notice.

Water simply moves where it should.

As a result, the property dries more quickly.

Meanwhile, garden beds stay intact.

Better still, outdoor spaces become more usable.

That’s good landscape design doing exactly what it was intended to do.

Drainage Is Only One Part of Managing Water Around Retaining Walls

One point that’s worth understanding is the difference between retaining wall drainage and whole-of-property drainage.

The drainage installed behind a retaining wall has one specific purpose.

It relieves hydrostatic pressure by allowing subsurface water to move through the aggregate drainage layer.

By comparison, managing surface water across the entire property is a completely different challenge.

Ideally, those drainage systems work together.

In a perfect world, agricultural drainage behind the wall connects into the stormwater network.

Sometimes that’s practical.

In other situations, site conditions make that connection expensive or difficult.

Ultimately, every property is different.

That’s why each retaining wall should be assessed individually rather than assuming every project requires exactly the same drainage solution.

The Best Thing You Can Do Before a Retaining Wall Inspection

If your property regularly experiences water problems, one of the most valuable things you can provide isn’t another explanation.

The best evidence comes from seeing the problem during a storm.

Take photos whenever possible.

Film short videos during heavy rain.

Show where water enters the property.

Capture where it pools.

Then record where it overflows.

Finally, show where it leaves the site.

Contractors can learn more from two minutes of storm footage than they can from twenty minutes of trying to imagine what happens during a dry inspection.

That footage replaces assumptions with real evidence.

As a result, it often leads to better recommendations.

Final Thoughts on Water Around Retaining Walls

Retaining walls are designed to support soil.

However, they only perform as well as the landscape surrounding them.

If there’s one lesson I’d leave homeowners with, it’s this:

Don’t just ask your contractor how they’ll build the wall.

Walk the property together instead.

While you’re there, discuss where the water comes from, where it needs to go and what you’re planning to build in the future.

The more information you can provide, the better the outcome is likely to be.

After all, the best retaining wall projects aren’t just about building a stronger wall.

They’re about creating a property where water around retaining walls is managed quietly, predictably and effectively for years to come.

Frequently Asked Questions

What causes water around retaining walls?

Water around retaining walls can come from roofs, neighbouring properties, driveways, gardens or natural ground levels. The visible wet area isn’t always where the problem starts, which is why a whole-site assessment is so important.

Does every retaining wall need drainage?

Yes. Drainage behind a retaining wall relieves hydrostatic pressure within the retained soil. Without it, water pressure can build and reduce the wall’s long-term performance.

Can landscaping affect water around retaining walls?

Absolutely. Garden beds, paving, lawns, retaining walls and other landscape features all influence how water flows across a property. Good landscape design guides water rather than fighting it.

Should I photograph flooding before my site inspection?

Definitely. Photos and videos captured during heavy rain often reveal information that isn’t visible on a dry day and can help identify the true source of the problem.

Can one drainage solution solve every water issue?

Usually not. The best outcomes are achieved by combining surface grading, drainage, landscaping and retaining wall design to manage water as a complete system.

Have a question or a topic you’d like us to cover? Email us at advice@conker.com.au.