Leak detection field testing and new-construction code testing are two different procedures. The hold window, the tools, and what a stable gauge actually proves are not the same.
Learn the H.U.N.T.E.R. Method →In leak detection field testing, once a line is isolated with expanding plugs and brought to controlled pressure, the technician monitors the gauge for approximately 3-5 minutes to confirm stability. If the gauge holds steady during that window, the line is considered to be holding. If it drops, the setup is verified before the pipe is blamed. This is a diagnostic field test -- it is not the same as a new-construction or code-required pressure test, which may specify longer hold times and different equipment entirely.
New-construction or code-required pressure testing typically uses permanent PVC manifolds with glued caps and fittings, may require holds of 15-30+ minutes under specific PSI requirements, and is subject to Florida building code or local jurisdiction inspection standards. Plumbers performing code-required tests follow those specifications exactly.
Leak detection field testing uses removable expanding plugs -- rubber, nylon, or pneumatic -- inserted temporarily at the pool end and isolated at the equipment pad. These plugs have their own pressure ratings and the test is diagnostic in nature, not a code-compliance event. The standard is: does this isolated line hold pressure under controlled conditions long enough to confirm the result?
A technician performing leak detection on an existing pool is running the second type of test. Conflating the two leads to over-pressurizing old plumbing, false expectations about hold times, and misunderstanding what the gauge result means.
In field leak detection practice, once the line is properly isolated, the plugs are seated, and the line is brought to controlled pressure, the technician observes the gauge for a window of approximately 3-5 minutes to confirm stability.
This window is sufficient to reveal a clear, consistent pressure drop in most field situations. A line with a significant break will show movement on the gauge within that window. A line with a minor slow leak may show a smaller movement that still warrants further investigation and setup verification.
The hold time is not the defining criterion. What matters is whether the gauge is stable or dropping -- and whether the setup has been verified before the pipe is condemned.
A pressure drop during the hold window does not automatically mean the underground pipe is broken. The drop may come from the test apparatus itself. This is one of the most important principles in professional leak detection practice.
Only after eliminating gauge leaks, hose leaks, coupling leaks, and plug seating issues should pressure loss be attributed to the plumbing system. This is not optional -- it is the standard that protects both the customer and the technician from unnecessary excavation.
Glued PVC caps and fittings, rigid manifold, designed for sustained high-pressure holds under inspection requirements. PSI may reach 35 PSI or higher per code specification. Hold times per inspector or project spec.
Temporary rubber, nylon, or pneumatic plugs. Rated to their own maximum PSI -- typically well below code-test levels. The hold window is diagnostic: 3-5 minutes of gauge stability confirms the line is holding under field conditions.
A technician using expanding plugs must respect the plug's rated pressure limit. Exceeding that limit doesn't produce a better test -- it blows the plug out and potentially damages the fitting, and it is not what the tool was designed for.
Ask how fast the pool is losing water and when. Fast loss and slow loss require different diagnostic urgency -- but the same verification discipline.
Know which type of test you are running -- field diagnostic with expanding plugs, or code-required construction test. The hold standard and equipment are different.
Select the line that matches the symptoms. Test one line at a time. The hold window only means something if the isolation was correct.
Bring the line to controlled pressure, observe for 3-5 minutes. If the gauge drops, verify the gauge, hose, plugs, and setup before condemning the pipe.
A stable gauge clears the isolated line for the test window. A confirmed drop after setup verification points to the pipe. Locate before excavating.
Document the result, repair the confirmed break, and retest under the same conditions. The post-repair test should show a stable gauge for the same window.
Pressurizes the line, watches the gauge for a few seconds, calls the result. Does not verify the setup when the gauge drops. Confuses a new-construction hold standard with a diagnostic field test.
Verifies gauge, hose, coupling, and plug seating before trusting any result. Observes for a consistent 3-5 minute window. Never condemns an underground pipe until the test apparatus itself has been eliminated as the source of the pressure loss.
Jeff David is the founder of Leak Business Academy, LLC and Leak and Subsurface Locators, LLC. He is a licensed pool contractor in Florida and an FSPA Palm Beach board member. Jeff teaches the H.U.N.T.E.R. Method -- including the critical difference between code-required construction pressure tests and diagnostic field tests using expanding plugs, the 3-5 minute stability window as the field standard, and why verifying the test apparatus always comes before condemning the pipe.
LBA training covers the complete pressure testing workflow including plug selection, setup verification discipline, hold interpretation, and documentation standards that protect every repair decision.
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