Above ground pool plumbing leaks(90134)
Credit: Allen-Douglas

Knowing how to find a leak in a pool can save money by avoiding hiring an expensive pool expert.  Finding the source of a pool leak is a time-consuming process with potentially large expenses, but here are some easy places to look before calling in pool experts.  

Simple Bucket Test to Find Out if there is a Pool Leak

Before spending too much time and money looking for the pool leak, do a simple test to find out if there is a leak and how much water is leaking.  Start by filling the pool water to a normal level.  Place a 5 gallon bucket in the shallow end of the pool or on a step.  An old chlorine bucket works well.  The bucket will need to be about two-thirds submerged in the water so a stand may be needed.  In the bottom of the bucket, place a rock to keep it from floating in the water.  Fill up the bucket two-thirds or more full with pool water to match the water level in the pool   Some water will regularly evaporate.  The bucket test will help to know if the loss of water is from evaporation or from a leak.   After a few days, if the bucket has more water than the pool level, there is a leak.  If the bucket has the same level of water as the pool, the water loss is a result of evaporation.  If this is the case, consider covering the pool with a plastic pool cover when not in use to keep the water from evaporating.

Skimmer Box Leaks

The skimmer box is typically poured or connected to the main pool by the contractor separately.  This design leads to a joint that will easily crack, resulting in leaking water.  Even gunite pools have leaking problems near the skimmer box.  Pool contractors generally do not adequately compact the soil under this area causing settlement of the box.  The settlement leads to cracking and leaking of water around this location.  

Allow the water to lower below the skimmer box to carefully inspect the joint for leaks.  If the water is above the skimmer box use a snorkel mask to visually inspect the joint for cracks, holes, or chips in the pool surface or liner.

pool plumbing leaks
Credit: Allen-Douglas

Above Ground Pool Plumbing Leaks

There is another place to quickly look for water leaks.  The above ground plumbing typically includes the pump, filters, and heater (if equipped).  There are PVC plumbing pipes in newer pools that connect all the mechanical parts.  A leak is possible in any of these items.  Leaks in the above ground plumbing are easier to see if it is on a concrete slab.  For plumbing not on a slab, first run the system and look for obviously leaks.  If there is no sign of running water, look for slower leaks.  Place colored construction paper under all the parts above ground.  Run the pool pump for 10-15 minutes.  Inspect the colored paper for any wet spots.  The inspection helps isolate the leaking part.

Pool Liner Leaks

Leaks in a pool liner take a little effort to find, but do not need a pool expert.  Use a snorkel mask with a clear display to visually inspect the entire surface of the liner under the water.  There may be several punctures in the liner so if one is found note its location, but continue inspecting the entire surface.  Pool liner leaks are a result of pool cleaning brushes and nets, pool toys, poor construction, and aging of the material  Look and feel the liner surface for cuts, holes, and other issues.  If a possible leak is found, use food coloring to detect the leak.  Make sure the water is very still.  Find squeeze bottle food coloring and squeeze a few drops underwater near the possible puncture in the lining.  Observe the food coloring.  If the coloring moves toward and disappears out the liner, this is the location of a leak.

Gunite Pool Leak

Test for leaks in gunite pool plaster the same way that a pool liner is tested.  Find the location of the potential leaks.  Make sure the water is very still and drop a few drops of food coloring underwater near the suspect area.  Watch the movement of the food coloring.  If it moves toward the hole in the plaster then you likely have a leak.  Areas around jets, ladders, corners, and edges are most prone to plaster leaking. 

Leaks in Underwater Plumbing Including Floor Drains

Swimming pool leaks that are under the pool in buried plumbing or floor drains are the most difficult to detect.  For buried plumbing leaks, look around the pool for soft ground areas or areas that have more vegetation growth, particularly during dry periods.  This may show the area of the pool where the underground pipes are leaking.  Test floor drain leaks by temporarily sealing off the drain using a thick rubber mat.  Temporarily seal the edges of the mat with some petroleum jelly.  Perform the bucket test again to see if the leaking stops.  Underground swimming pool leaks are easily the most difficult to find.  Ground penetrating radar has performed well in some cases, to find wet pockets of soil underground.  This helps to isolate where the leak is located.  This type of testing can be expensive, but digging up around the entire pool to find an underground leak is more expensive.