How Off-Level Can a Fiberglass Pool Safely Be? Understanding the Risks

There’s no better way to cool off during the hot summer months than a refreshing dip into a swimming pool! While there are many different residential swimming pools, fiberglass pools are an extremely popular choice. Ensuring that your fiberglass pool is level at installation is critical. So, how off-level can a fiberglass pool safely be?

A fiberglass pool can safely be slightly off-level since it’s unlikely that any will be completely level. According to industry standards, fiberglass pools can be up to 1” (2.54 cm) off-level. However, most professional pool installation companies will aim for ½” (1.27 cm) or less. 

There are significant risks associated with off-level installations. I’ll cover what those are, and how you can tell if a fiberglass pool is level or not.

The industry standard for being off-level is up to 1" on fiberglass pools.
Photo Credit: Facebook

How Do You Know if a Fiberglass Pool Is Off-Level?

Off-level pools can be pretty noticeable when the waterline differs significantly from the shallow end to the deep end. Since this can cause structural damage, pool owners might also see cracks in the pool shell or notice that their automatic vacuum skimmer isn’t covering the entirety of the pool bottom. 

You will know if a fiberglass pool is significantly off-level because the waterline will be higher in one spot and lower than in another. This discrepancy indicates a slope causing the water to collect in the lower spot.

Check the level by measuring how far it is from the ground level to the waterline at different points around the perimeter. Check this measurement every two to three feet around the edge and note each number. If this measurement significantly differs at various points, the pool may not be level. 

You can use any tape measure to do this, but it’s best to use a stiff metal one to ensure an accurate measurement. I like this Craftsman 25-foot Tape Measure (on with a rubberized grip that makes it easier to hold. This tape measure also has a durable coating to protect it even if splashed with pool water. 

What Happens if a Fiberglass Pool Is Not Level?

A fiberglass pool that isn’t level can cause many problems, including structural damage to the fiberglass shell, damaging connected pipes, and damage to the electric system. 

Pools that are only slightly off-level and within the recommended 1” (2.54 cm) of pool level tolerances typically don’t have any problems. However, more than 1” (2.54 cm) off-level pools can see severe problems develop over time. 

Structural Damage to the Fiberglass Shell

One of the most severe problems is that an off-level pool can cause the fiberglass shell to crack. The pool water can leak out of the pool and into the surrounding area when this happens. Water can trickle down underneath the fiberglass pool shell, which will worsen the problem. 

Damage to the Connected Water Pipes

A pool that is off level can also cause damage to the PVC water pipes that connect the pool’s water pump. This pump is critical to ensuring the water circulates regularly and doesn’t become a breeding ground for insects, such as mosquitos. If the pipes become damaged, the pump may not be able to function correctly. 

Pipe damage can also cause problems when it’s time to drain the pool, as they may no longer be aligned correctly. This damage can amplify the pool problems as it will be harder to remove the water to make any repairs to the pool. 

Damage to Electric Systems

As with the attached water pipes, an off-level pool can pull the electric wires out of place. Pools use electricity in more ways than people realize. Pool lights are controlled by electricity, and disconnected or damaged wires can cause them to stop functioning. 

In addition, the pool pump is also connected with wires. The wires can separate if the pool becomes too off-level, and the pump won’t operate. 

Non-Structural Problems

Although structural problems are more critical, off-level fiberglass pools can also be challenging to keep clean. Many pool owners use in-pool vacuums and skimmers to remove any dirt or other debris that falls into the pool. When the pool isn’t level, these tools can’t navigate around the bottom of the pool. This can cause dirt to build up to the point that a pool must be drained entirely to clean it. 

Structural problems can arise if a fiberglass pool is off-level.
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How Can You Level a Fiberglass Pool? 

You can level a fiberglass pool using three primary steps:

  1. Set the pool mold into the hole correctly.
  2. Walk the entire pool floor.
  3. Check the level of the pool shell.

First, the fiberglass pool mold must be carefully inserted into the in-ground hole. The mold is usually picked up by a heavy-duty crane for large pools and placed gently into the hole. The installers will have measurements of both the hole and the fiberglass mold. They can use these to make sure the mold is seated correctly within the hole, using the crane to make adjustments. 

Fiberglass pools are inserted into the in-ground hole by the use of a crane.
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Next, the pool installer will climb inside the fiberglass mold and walk the entire pool floor. They often take their shoes off for this process to feel the floor more accurately. They’re looking for any areas where there are depressions or bumps that indicate the pool isn’t resting firmly on the base. 

Finally, the pool installer will use a level around the outside edge of the pool shell to ensure it is completely aligned. They must check different points around the perimeter to confirm that both the shallow and deep ends are level. 

If the pool doesn’t pass these checks, the fiberglass shell will be removed. The installer will adjust the hole and reseat the shell before running through these three checks again. 

To see how a fiberglass pool shell is inserted into its hole and leveled, check out this video from American Pool and Spa KY:

Final Thoughts

Fiberglass pools can safely be off-level by up to 1” (2.54 cm). Professional pool installers will work to make a fiberglass pool as level as possible and frequently achieve results that are ½” (1.27 cm) and less off-level. Homeowners can rarely notice that a fiberglass pool isn’t completely level when they are off by 1” (2.54 cm) or less.