Believe it or not, many pool problems start before the water ever goes in. If you don’t prepare the ground for a swimming pool the right way, you’re setting yourself up for uneven walls, drainage issues, or complete structural failure. And yes, this applies to both above-ground and in-ground pools.

This guide breaks down what proper prep looks like, how it shifts between above-ground and in-ground installs, and why it’s worth getting right the first time.

Ground Prep Basics

Before any digging happens (or even a tape measure comes out, really), the site needs to be cleared and stabilized. This early work sets the stage for a safe, long-lasting pool, and it applies whether you’re installing an above-ground frame or a permanent inground shell.

To properly prepare the physical site for any type of pool installation, you need to:

• Clear the area down to bare soil. Remove all grass, roots, rocks, and debris. Nothing unstable should be left beneath the pool.
• Level the ground with precision. Use a board level or transit to achieve no more than a ¾-inch difference across the entire footprint.
• Assess soil stability and drainage. If water pools or the soil feels too soft, you may need to bring in crushed stone or drainage piping.
• Plan for construction access. Make sure there’s room for trucks, excavators, and material deliveries to reach the site safely.
• Mark all underground utilities. Call your local locate service before any digging begins, as hitting a line can halt everything.

This is the kind of basic ground prep that every pool requires before anything else happens. Get this part right, and everything that follows becomes easier and more reliable.

Above Ground Pool Prep

Even after you have the basics down, installing an above-ground pool requires a little extra prep work. If you want the frame to hold up evenly and the liner to last more than a season, that is.

Here are the steps to follow to prepare the ground for an above-ground pool:

1. Check the level again after clearing. Even minor slopes can distort the shape of the pool and lead to uneven water levels.
2. Add a cushioning layer. Spread about 1–2 inches of sand or stone dust across the base. This protects the liner and smooths the surface.
3. Lay down a ground cloth or pad. This barrier helps prevent root intrusion, punctures, and liner abrasion.
4. Compact the surface gently. Use a hand tamper or light roller to create a firm, even base. You want it solid, but not rock-hard.

When done right, this setup protects the structure and minimizes wear on the liner, especially in high-traffic areas.

In-ground Pool Prep

In-ground installs call for more equipment and precision, but the steps are just as essential. They’re also more permanent, so you want to try to get this right the first time.

Follow these steps to prepare the ground for an in-ground pool:

1. Excavate to the design specifications. Follow the exact shape, depth, and slope layout from the pool plans, including steps or benches.
2. Check and reinforce the soil. If the subsoil is sandy, loose, or overly damp, install crushed stone or geotextile fabric to improve stability.
3. Set up proper drainage. Install a French drain system or perforated pipe in gravel trenches to keep water from building up beneath the shell.
4. Compact the base in lifts. Backfill or crushed stone should be compacted in layers (usually about 6 to 12 inches deep) before moving to the next.
5. Level everything one last time. Before the shell or forms are placed, verify every dimension and surface for accuracy.

Precision in these early stages is what ensures the shell sits evenly and holds up over time.

What Happens When Ground Prep Is Skipped

It’s worth repeating: most structural issues with pools trace back to poor prep. Maybe the base wasn’t level. Maybe the soil wasn’t stable. Or maybe no one thought to check the drainage until after the first storm. And it’s not like these are rare problems — they’re probably more common than you’d think. Not to mention, expensive to fix.

Improper prep can lead to leaning walls, wrinkles in liners, cracks in shells, or even full structural failure. And most of those problems won’t show up right away. They surface after a season or two, long after the concrete’s poured or the water’s filled.

Ultimately, good ground prep isn’t just about following a checklist. It’s about understanding that once the pool is in, fixing what’s underneath it gets a whole lot harder. That’s why this step matters more than any other.

The Bottom Line

If you want your pool to last, you have to prepare the ground for a swimming pool like it matters, because it does. From above-ground frames to full inground builds, stability starts with the soil, the slope, and the space you build on.

And if you need help with your pool project, Clark Pools and Spas offers professional installation services. We can walk you through what’s needed to get your site ready before proceeding with installation. Contact us to get started today.

After all, a solid install starts with solid prep, and it’s worth doing right.