Where Does Water Go When the Pool Leaks?  (Important Signs to Watch Out for)

Pools provide endless fun in the summer heat.  That is, until you walk out to the pool deck and see that the water level looks noticeably lower than it did just yesterday.

When things go awry with a pool, enjoyment can quickly turn into expensive frustration. This can be particularly true when there’s a leak in the pool, especially when it can’t be located.

While evaporation can sometimes be confused for a leak, losing more than one-quarter inch should be investigated.

And while there’s urgency in finding the leak itself, you may wonder “Where does water go when the pool leaks?”

Water will travel through the crack and into the surrounding area.  But, it’s important to understand the potential consequences of the pool leak, including the subsequent damage that can ensue.

In this post, we’ll review where water goes when the pool leaks and clues to look for that’ll help prevent it from spiraling into larger issues.

Let’s dive in!

Signs of a Pool Leak

Pool leaks ultimately result in a loss of water.  But, there are several signs that can help you identify whether you have a leak.  

Unexplained Water Loss

Often the tell-tale sign of a pool leak is unexplained water loss.  A pool party with lots of splashing is one thing, but if the pool has had calm activity and the water level is plummeting, this should put you on high alert.

You can keep track of the water level by marking the water line with a piece of tape and checking it daily.  A bucket test can be performed to ensure it’s not just evaporation. 

Visible Damage

If you’re fortunate enough to actually notice damage to the pool liner or structure, this is an immediate sign of a potential leak.  This could be a crack in the walls or floors, or simply a tear in the liner.

However, there are many instances where a hole or crack doesn’t readily stand out. A small pinhole at the bottom of the pool is enough to cause the water level to gradually drop, but is unlikely to be noticed by swimmers.

A large enough leak could even cause damage to adjacent structures, such as your house.

Soggy Ground

Wet or damp spots around the pool could signify a potential leak, assuming they can’t be attributed to rain or splashing.

If you’ve had dry weather, monitor the damp spot for a couple days to see if it goes away or remains wet.  If it remains wet, it can clue you into the potential location of the leak at the pool.

Signs of water at the equipment pad are also likely to indicate a leak.

Structural Shifts

Pool decking that has shifted could be a sign of a leak.  Water can cause the underlying soil to become saturated resulting in gradual shifting of adjacent structures.

A leak also has the potential to cause soil to washout underneath the decking.  This could cause a void underneath the foundation leading to sizable damage.  

High Water Bills

If you use a garden hose to fill up the pool, it’s likely that you’ll notice a higher frequency of topping off the pool if there’s a leak.  

However, if you have an automatic fill system you may not notice increased water usage until the water bill comes in the mail.  The fill system may be continuously adding water to compensate for the lost water due to a leak.

Where Does Water Go When Pool Leaks?

Understanding where water goes when there is a pool leak is important. Unsurprisingly, water will follow the path of least resistance.

While some may think leaking water just disappears into the ground, there’s more to consider such as location of the leak and the type of pool.

Leaks at Pool Equipment, Plumbing and Fixtures

If a leak has sprung at the equipment pad, you’ll likely see the presence of moisture even if it hasn’t rained.  Depending on whether the leak is on the suction or pressure side of the pump may change when the leak is visible.

If the leak is on the pressure-side of the pump, you’ll probably see water dripping when the pump is running.  A drip can also occur from the pressure-side even if the pump is off, if the location of the leak is at a lower elevation than the pool’s water level.

If the leak is on the suction-side, you may only notice water dripping when the pump is off.  You may also see bubbles coming from the return jets as air is sucked into the system while the pump is running.

The leaks could occur at damaged o-rings on the equipment lids or drain plugs, at fittings, or even cracks in the plumbing.  Those that occur above ground will be much easier to diagnose than the ones hidden underground.

If the leak is just a small periodic drip, water may pool up on the concrete pad but evaporate over time.  Otherwise, if it’s a large enough leak it could run off to the adjacent ground.

Leaks in underground plumbing or at fixtures, such as pool lights and skimmer boxes, will often flow into the surrounding soil.  

If the leak is on a return line back to the pool high quantities of water could spray out and wash away the surrounding soil. 

Water leaking by fixtures is not under high pressure and may slowly seep into soil with less chance of causing too much damage.

Leaks in Vinyl Pool  

In-ground vinyl-lined pools often have a vermiculite floor with plastic or steel walls for support.  

The vermiculite floor provides a firm, but comfortable walking surface.  If there is damage to the floor of the liner, water will pass through the porous vermiculite into the soil.  The porosity of the base should prevent water from being trapped underneath, which means the pool will see continuous loss of water until the leak is fixed.  

If the liner has a hole in a side wall, there’s potential water could become trapped resulting in a bubble behind the liner.  Depending on the size of the hole, the water simply may sit there without actually causing much loss of water in the pool.  It may not be until the liner is replaced that you see signs of corrosion in the wall structure.  

Above-Ground Pool

A leak in the floor of an above-ground pool could present itself differently based on the type of underlayment used.  Oftentimes, a porous base is installed that would allow water to flow through.  

Sometimes a foam base may be installed that could trap water and prevent it from going directly into the soil.  Instead it could become trapped underneath the liner, or could escape from the perimeter of the base.  

A leak in an above-ground pool often results in soft spots underneath the liner or around the base of the pool.  

Leaks in Concrete Pool

Concrete pools are generally installed on top of compacted soil with steel rebar reinforcement.  If there is a crack in the concrete that runs through the entire thickness, it could allow water to escape into the surrounding soil.

If the leak is left untreated for too long, there’s potential that soil underneath the pool could washout leaving a portion of the shell unsupported. This could increase the risk of structural damage to the concrete, although the underlying rebar should help reduce the risk.

Leaks in Fiberglass Pool

Fiberglass pools are often placed on top of a gravel bed.  The gravel provides a firm, but porous surface.

If there is a crack in the fiberglass pool, the water will likely flow into the soil underneath the gravel.  

This scenario can wreak havoc if the water table underneath the pool is high and the leak is left unresolved.  If the water table overcomes the level of water in the pool, the fiberglass shell can actually pop out of the ground resulting in a costly repair or replacement.

Steps to Take if You Suspect a Leak

Losing more than one-quarter inch of water per day often points to a leak rather than evaporation.  A bucket test is a great way to rule out water loss due to evaporation.

Comparing the loss of water with the pump on/off and return lines open/plugged can also help hone in on location of the leak.

If the bucket test confirms a leak, you’ll need to perform a close inspection of the entire pool system for any clues of a leak.  Check the nearby landscaping for any soft spots that could signify a leak underground.

You can use dye underwater to help locate leaks in the pool liner or structure.  

If you can’t locate the leak, don’t be afraid to call out a professional leak detection company.  While it may be costly to find the leak, it could be even more costly to leave it unattended.

Once the leak is located, you’ll want to take appropriate measures to repair it.

Final Takeaway

Having a leak in the pool can be one of the most frustrating experiences for a pool owner, especially when they’re difficult to locate. 

Determining where water goes when there’s a pool leak can vary based on the type of pool and location of the leak. A leak in the floor of a pool will often result in water traveling down into the soil, whereas a leak in the wall of a vinyl liner could cause water to become trapped between the wall and liner.

Regardless of where the water goes, it’s important to address the leak as it can cause issues keeping the water balanced and can cause the water bill to skyrocket.  Furthermore, a sizable leak can snowball into damage of adjacent pool decking and landscaping.

Happy Swimming!