Yes -- underwater microphones called hydrophones amplify the sound of pool leaks that are invisible to the eye. They're a standard part of every professional pool leak detection visit.
Many homeowners assume pool leak detection is mostly visual -- a technician looking for cracks and checking fittings. Acoustic equipment changes that picture entirely. Underwater microphones allow a trained technician to hear leaks that are completely invisible, and to do so with enough sensitivity that even slow, gradual water loss from a small crack registers as a detectable signal.
A waterproof transducer designed for use submerged in the pool. Picks up sounds through water -- leak noise at fittings, cracks in the shell, light niches, and main drains. Connected to an amplifier and noise-isolating headphones.
Pressed flat against deck surfaces over buried plumbing paths. Picks up sounds traveling through soil and concrete from underground pipe breaks. Used to narrow the area of interest before trace gas equipment pinpoints the exact location.
At Leak and Subsurface Locators, acoustic equipment is used in a specific order within the broader diagnostic process -- not in isolation.
Before acoustic listening begins, the pump is turned off. The pool quiets down -- pump vibration and return flow stop, eliminating the largest source of background noise. In this quiet state, the hydrophone can detect sounds that would otherwise be masked.
The technician enters the water and moves the hydrophone systematically -- floor, walls, every return jet, skimmer throat, light niche, main drain cover, and cleaner port. At each location, the hydrophone is held still while the technician listens. An active leak sounds like a distinct hiss, rush, or subtle pulling noise -- different from normal pool acoustics. When a signal is detected, the location is noted for dye confirmation.
Wherever the hydrophone detects a signal, dye testing confirms it visually. This pairing -- acoustic signal plus visual dye confirmation -- documents structural leaks with two forms of evidence before they're recorded as confirmed findings.
After the underwater sweep, a ground microphone is pressed against the deck over the path of buried pool plumbing. If a pipe is actively losing pressure underground, the escaping air or water produces sound that travels through the soil and into the concrete above it. The ground microphone picks that up and narrows the area before trace gas is used to pinpoint it precisely.
Acoustic tools are excellent for active, audible leaks -- cracks and fittings with enough water movement to produce a sound. Very slow leaks losing less than a quarter inch per day may not produce a detectable acoustic signal regardless of how sensitive the equipment is. For those cases, dye testing (visual) and pipe testing (pressure measurement) provide evidence where acoustic detection doesn't. The three methods together cover the full range of pool leak types.
Use these tools to understand your pool's water loss before your appointment.
Leak and Subsurface Locators uses hydrophones, ground microphones, dye testing, pipe testing, and trace gas equipment on every visit. Call Sandra to schedule.
Yes -- the pump is turned off before acoustic listening begins. The pump produces significant vibration and flow noise that interferes with the hydrophone signal. With the pump off, the pool quiets to a point where leak signals stand out. Testing with the pump running is possible in some situations but significantly less sensitive.
Yes. Hydrophones work on all pool types -- vinyl liner, fiberglass, gunite, and plaster-over-concrete. Liner tears and failing liner bead seats produce detectable acoustic signals. The sound characteristics differ slightly by pool type, but a trained technician identifies leak signals across all pool surfaces.
The same equipment is used. Commercial pools are larger and have more fittings to check, making the sweep longer -- but the acoustic tools and methodology are identical. Professional hydrophones from LeakTronics and Anderson are industry standards for both residential and commercial work.
Experience. Pool water makes sounds -- filtration, natural movement, settling. A leak has a specific signature: directional, often with a hiss or sucking quality, and it gets louder as you move the hydrophone closer to the source. Normal pool noise is more diffuse and doesn't intensify at a specific point. Distinguishing the two correctly is a skill built through testing many pools -- which is why specialist companies with high job volume develop more accurate ears than companies that do occasional leak detection as a side service.