Leak Tech LLC was called to investigate a pool that was losing approximately 1 inch of water per day in Scottsdale, Arizona. Pressure testing confirmed a damaged underground return line beneath the cool deck.
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Leak Tech LLC was called to investigate a pool losing approximately one inch of water per day in Scottsdale, Arizona. Through pressure testing and electronic leak detection, we located a broken underground return line beneath the cool deck and completed a permanent repair while minimizing damage to the surrounding deck area.

Using electronic leak detection and pressure testing, LeakTech LLC pinpointed the exact location of the underground return line leak beneath the cool deck. The leak location was marked with blue tape before excavation began, allowing us to minimize demolition and reduce repair costs for the homeowner.

After carefully cutting and removing the cool deck, the underground plumbing was exposed. The damaged section was located on the center return line where a 45-degree PVC fitting had cracked. Root intrusion from nearby landscaping was the most likely cause of the failure. The leak location is indicated by the blue arrow in the photo.

The damaged fitting was removed and replaced while preserving the surrounding plumbing. By carefully rebuilding only the failed section, we avoided unnecessary cutting or modification of adjacent pipes. Once the repair was completed and the adhesive fully cured, the line was pressure tested at 20 PSI for 25 minutes. The repair passed testing with no pressure loss, confirming the leak had been eliminated.

After the pressure test confirmed a successful repair, the excavation was backfilled with sand and concrete. The final step included restoring the cool deck texture to match the surrounding area as closely as possible. The pool plumbing was returned to service and the underground leak was permanently repaired.
Underground return lines are one of the most common sources of pool leaks in Scottsdale, Arizona. Because these pipes are buried beneath concrete and cool deck surfaces, they are exposed to ground movement, tree root intrusion, and years of temperature changes. One common cause of return line leaks is shifting soil. As the ground expands and contracts over time, stress can be placed on underground PVC pipes and fittings. Older plumbing systems are especially vulnerable because PVC becomes more brittle with age. Tree roots can also create significant pressure around underground pool plumbing. As roots grow, they may push against fittings and pipe joints, eventually causing cracks or separations. In many cases, leaks occur at elbows, couplings, or other connection points rather than in the pipe itself. Poor workmanship from previous repairs can also lead to future failures. Improperly glued fittings or low-quality materials may hold for years before eventually developing a leak. At LeakTech LLC, we use professional pressure testing and electronic leak detection equipment to locate underground return line leaks and perform permanent repairs while minimizing damage to the surrounding cool deck.
How do you locate a return line leak under a cool deck?
We use pressure testing and electronic leak detection equipment to pinpoint the exact location of underground return line leaks before excavation begins.
Can tree roots damage pool return lines?
Yes. Tree roots can place pressure on underground PVC plumbing and fittings, eventually causing cracks and leaks beneath the pool deck.
Do you have to remove the entire cool deck to repair a return line?
No. In most cases, we only remove the section directly above the leak location to minimize demolition and restoration costs.
How long does a cool deck return line repair take?
Most repairs can be completed within one day, including excavation, plumbing repair, pressure testing, and deck restoration preparation.