Underground pool pipe leaks leave no visible sign at the surface. Finding them requires acoustic listening, pipe testing, pipe locating, and when needed, trace gas -- each step narrowing the location before any concrete is cut.
A pool that loses water when the pump is running -- but holds when the pump is off -- is showing the signature of an underground plumbing leak. The pipe is somewhere underground, the break could be anywhere along its run, and there is no obvious surface clue pointing to where. This is the diagnostic problem that specialized leak detection is built to solve.
Before any testing or listening begins, the technician maps the exact route of the buried pool plumbing using an electronic pipe locator. A signal is introduced into the line and read at the surface, showing where each pipe runs beneath the concrete and how deep it sits. This is the foundation of everything that follows -- the technician cannot listen or test effectively without knowing where the pipe actually is.
With the pipe path mapped, the technician presses a ground microphone against the deck surface at intervals along the pipe run. A break in a pressurized line produces an acoustic signal -- a hiss or rushing sound -- that travels through the soil and into the concrete above it. The technician listens at multiple points, comparing signal strength to identify where the sound is loudest. This narrows the break to a general area before any other method is used. Acoustic listening is the primary method for locating where an underground break is.
Air is introduced into each pool plumbing line individually through LSL's custom-built manifold. The technician tests from multiple positions -- not always from the equipment pad -- and runs multiple tests on each line to cross-check results. A line that holds pressure is intact. A line that loses pressure has a break somewhere underground. Testing from different positions and running multiple tests is what gives LSL its accuracy and why excavation decisions are made with confidence rather than guesswork.
Trace gas is a specialized technique -- not used on every job. When acoustic listening has identified a general area and additional precision or confirmation is needed, trace gas is the next step. A blend of 5% hydrogen and 95% nitrogen, or helium, is introduced into the confirmed leaking line. Because waiting for gas to passively rise through concrete is impractical in the field, the technician drills small strategic holes in the slab to create controlled release points. The sensor detects the strongest signal at those points. When the gas is shut off, the last location showing residual concentration is typically the origin zone of the break. LSL is one of the only pool leak companies in South Florida with a full trace gas system -- other companies regularly call LSL to use their equipment on difficult jobs.
Once the zone is confirmed through acoustic and pipe testing, and trace gas if used, the location is marked on the deck surface. Findings are documented. Only after this evidence is gathered and cross-checked does the technician confirm an excavation location. The repair crew then opens a targeted section of concrete at the marked point -- not a long exploratory trench.
South Florida soil is primarily sandy, which generally allows acoustic signals to travel well. However, ground composition varies -- clay pockets, root systems, saturated soil after rain, and varying depths all affect how clearly an acoustic signal reaches the surface. When soil conditions hinder acoustic detection, trace gas provides a second layer of evidence that soil composition affects less directly.
Check your pool's water loss pattern before calling -- these tools help confirm whether underground plumbing is likely involved.
Leak and Subsurface Locators uses acoustic listening, pipe testing, and trace gas to locate underground pool pipe leaks with accuracy. Call Sandra to schedule.
The pump on/off test gives the first clue. If the pool loses more water when the pump is running than when it is off, the leak is likely in the pressurized plumbing side. If the pool loses water at the same rate regardless of pump state, the leak is more likely structural -- a crack or fitting failure in the pool shell. A professional visit tests both to make sure nothing is missed.
Yes. Some underground pipe breaks lose pressure very slowly -- just a fraction of an inch per day at the pool surface. Very slow drops are among the most difficult to locate precisely because the acoustic signal is faint and the pressure change on the gauge is small. These situations require patience, multiple tests, and sometimes trace gas to build enough evidence for a confident location. Not every underground leak can be located on the same visit -- particularly very small pressure drops that are at the limits of detection.
Pool service companies are equipped for maintenance -- they typically don't carry ground microphones, pressure manifolds, pipe locators, or trace gas equipment. Finding underground pipe leaks requires all of these tools plus the training to interpret what they tell you. A pool service company that cannot find the leak is not doing anything wrong -- they are simply not equipped for this type of diagnostic work. That is why a specialist is needed.
Yes -- to repair a broken underground pipe, access to the pipe is required, which means opening the concrete or soil above it. The goal of leak detection is to make that excavation as small and targeted as possible. With the break zone accurately identified, the repair crew opens a small section directly over the failure point rather than cutting long exploratory trenches.