They just wanted a pool.
A family I visited recently had been dreaming about backyard memories: sunny days, laughter, splashing kids, maybe even a few quiet moments once the chaos wore off.
Instead? They ended up in a legal battle, their patio is sinking, and the beautiful fiberglass pool they invested in just months prior might need to be pulled out entirely.
And the worst part? It all came down to a single mistake that happened below the surface—the kind you don’t know to ask about until it’s too late.
As someone who’s been in the fiberglass pool industry for years, I’ve seen this scenario play out too many times. That’s why I’m writing this article—not to scare you, but to equip you.
Because you deserve to know how to protect your investment before ground is ever broken.
What Went Wrong With This Pool Installation?
When I arrived at the homeowner’s property, it looked fine from a distance. But as I stepped closer to the edge of the patio, something didn’t feel right. I lightly tapped the concrete.
Hollow.
Eighteen inches of air underneath. Around the entire pool.
I looked at the owner and asked, “What did they use for backfill?”
They paused. “I think... dirt?”
And there it was.
What Is Backfill—And Why Does It Matter So Much?
When you install a fiberglass pool, you dig a hole larger than the pool shell itself. The space between the pool and the ground is then filled with material—this is called backfill.
It’s not just filler. It’s structural support.
If the wrong material is used, it settles. And when that happens, everything above it—your pool, your patio, your dreams—goes with it.
In this case? The installer backfilled with the same dirt and clay they dug out of the ground. No crushed gravel. No compaction strategy. Just shortcuts.
The Three Backfill Methods (And Which One to Avoid at All Costs)
Let’s talk about your options.
The Right Way: Clean Crushed Gravel
This is the gold standard.
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It compacts evenly
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It doesn’t settle over time
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It drains beautifully
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It protects your pool and patio for the long haul
Crushed stone is what we recommend at River Pools—and it’s what any quality fiberglass pool installer should be using.
Read more about the installation methods preferred around the industry.
The Not-So-Great Way: Sand
Sand is easy to work with, and in certain soil types, it can perform okay. But it doesn’t hold up well in wet climates or clay-rich soils.
I've seen too many shifting decks and cracked patios to give it my full approval.
The Wrong Way: Dirt, Clay, or Fill
This is what happened to the family I mentioned.
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It settles unpredictably
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It doesn’t drain well
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It most likely voids warranties and can lead to massive damage
No professional fiberglass pool installer should ever use it.
What Should You Ask Before Signing a Contract?
Here’s the thing: most homeowners don’t know to ask about backfill.
That’s not your fault. But let’s fix that now.
Ask these three questions:
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What material will you use for backfill?
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Is it clean crushed gravel or something else?
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How do you ensure the backfill won’t settle?
If the installer gives you vague answers or says dirt is “fine,” that’s a red flag.
Read more: Additional Questions to Ask Your Builder
How My Company Handles Backfill (and Why We Stick to Industry Standards)
Over the years, I’ve seen just about every way a fiberglass pool can be installed—some good, some… not so good.
At my company, we stick with the methods that have proven themselves time and time again—not just through our own experience, but through what’s now widely accepted as best practice across the fiberglass pool industry.
And that starts with one critical choice: the backfill material.
We follow the same recommendation you’ll hear from the top manufacturers, engineers, and installers nationwide:
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Use clean, crushed gravel
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Compact it in layers
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Avoid dirt, clay, or other materials that will settle
These aren’t just preferences—they’re standards that protect homeowners from the kind of heartache I described earlier.
Bottom line: We follow these practices because they work. They prevent problems before they start. And most importantly, they give our customers peace of mind.
Because no one should have to worry about what’s happening beneath their patio six months after installation.
Why So Many Homeowners Still Get Burned
Here’s the harsh truth: a lot of pool builders are racing to finish jobs quickly. They’ll promise the lowest price and fastest install—but they’re not thinking about five years down the line when your patio starts to sink.
And by then, your contractor might be long gone, and the workmanship warranty? Voided.
That’s why education matters. It’s why you’re here, reading this.
You deserve to know.
The Good News: This Mistake Is 100% Avoidable
When homeowners are informed, they win. When installers are held to a standard, everybody wins.
So here’s what I want for you:
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Don’t just pick a pool—pick the right team.
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Ask about backfill. Demand gravel.
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Take your time. Protect your investment.
Because you’re not just installing a pool. You’re creating a space for joy, for family, for life.
And that’s worth getting right.
From the Author – A Message from Marcus Sheridan
Hey, Marcus here.
I wrote this because I’ve seen too many good people get stuck with bad installations. And in every case, they trusted someone who said, “Don’t worry about it.”
I want you to worry about it. I want you to ask the hard questions.
Because that’s how you avoid situations like the one I walked into recently.
I’ve been in this industry for 2 decades, and I’ve seen the good, the bad, and the ugly. But I’ve also seen what happens when homeowners are empowered with knowledge—and that’s why I keep writing.
Stay curious. Stay smart. And if you ever need a straight answer, you know where to look.
From the Manufacturer
River Pools® is a leading manufacturer of world-class fiberglass pool shells, proudly built in Fortville, Indiana.
We do not install pools ourselves, but we work closely with a network of independently owned and operated installers across North America.
Our mission is simple: to help families enjoy the pool experience they deserve—through quality products, expert resources, and complete transparency.
Ready to Get Started?
If you’re thinking about installing a fiberglass pool, we’re here to help.
Browse our fiberglass pool models.
