Can I Backfill My Pool With Dirt?

Don't be this guy. Just say No to using dirt as backfill.

Can I backfill my pool with Dirt?

It’s a question many homeowners ask when researching fiberglass pool installation:

“Can I backfill the pool with dirt from the excavation?” On the surface, it might seem logical. After all, when a hole is dug to install the pool, there is usually plenty of soil available. But when it comes to installing a fiberglass pool properly, or any pool for that matter, backfill material matters a lot more than most people realize. In fact, the material used around the pool walls plays a major role in how the pool performs for years to come. So let’s walk through the answer.

What Is Pool Backfill?

Backfill refers to the material placed around the outside walls of the pool shell after it has been set into the ground. Its job is to:

• support the pool walls

• stabilize the structure

• allow proper drainage

• prevent shifting or settlement

Because fiberglass pools rely on even pressure around the shell, the backfill material must provide consistent uniform support. Which is why the answer to the question Can I backfill my pool with dirt is a hard NO!

When Can I backfill my pool with dirt?

Never, absolutely never! Now here is why!

Why Dirt Is Not Recommended

While it may seem convenient to reuse excavated soil, dirt is rarely the best choice for pool backfill. Its a major corner cut and directly affect the long term quality of your pool installation.

Here’s why.

1. Dirt Holds Moisture

Most soil contains a mix of clay, silt, and organic material. These materials tend to hold water instead of draining it. When water becomes trapped around a pool shell, it can create uneven pressure on the walls.

Over time this can contribute to:

• shifting

• settlement

• structural stress

• Build up of hydrostatic pressure outside the pool

Proper drainage is one of the most important factors in a long-lasting pool installation.

2. Dirt Can Settle Unevenly

Excavated soil usually contains a mix of:

• rocks

• roots

• organic material

• clay

• loose soil

When this material is placed back around the pool, it often settles unevenly over time.

This uneven settling can create areas where the pool is not fully supported. It leaves voids under the pool patio. Void that can lead to cracks in concrete pool decks, settling of paver patios and more.

3. Dirt Is Difficult to Compact Properly

Another issue is compaction.Dirt backfill often requires mechanical compaction to stabilize it. However, compacting soil around a fiberglass pool can be tricky because excessive pressure could damage the pool shell.This is one reason legitimate installers refuse to use anything but clean fractured stone

.

Why Reputable Pool Builders Use Clean Stone Instead

Instead of dirt, reputable fiberglass pool installers use clean crushed stone for backfill. Clean stone typically consists of ¾-inch crushed gravel with no fine particles.This material offers several advantages.

Excellent Drainage

Clean stone allows water to move freely through the material rather than trapping it around the pool.

This helps prevent hydrostatic pressure buildup.

Strong Structural Support

Crushed stone particles have angular edges that lock together.

Once installed, the stone creates a stable support system around the pool walls.

Instant Compaction

Clean fractured stone is 97% compacted on placement

Reduced Risk of Settlement

Because clean stone does not compact like soil, it tends to remain stable over time.

This reduces the chances of the pool shifting or settling.

Are There Situations Where Dirt Is Used?

There is never a case where native soil should be used as direct backfill for the pool. Outside of the clean stone backfill area, native soils can be used to rough grade a sloped area but never should be used as direct backfill against any type of pool.

Questions Homeowners Should Ask Their Pool Builder

If you’re planning to install a fiberglass pool, here are a few good questions to ask:

• What material do you use for backfill?

• How do you ensure proper drainage around the pool?

• What steps prevent settling over time?

• Does your installation method follow manufacturer guidelines?

Understanding the installation process like "The Pool Pros Way" can help you feel confident that the pool will perform well long-term.

The Moral of the Story

While it may seem convenient to backfill a fiberglass pool with dirt from the excavation, it should never be used. Reputable pool installers instead use clean fractured stone, which offers better drainage, improved structural support, and reduced settlement risk. Because the area around the pool will eventually be covered by decking and landscaping, it’s easy to overlook what’s happening underground.

But in reality, the materials beneath and around the pool are some of the most important parts of the entire installation.

SHAMELESS CALL TO ACTION

Pool Pros team of in house pool designers is ready to help you create the backyard of your dreams. Call our office anytime @ 920-771-0107 to start a conversation about your pool project.