Pipe testing uses air pressure to check each underground pool plumbing line individually -- confirming which pipes are intact and which ones have a break before any digging starts.
Underground pool pipe leaks are invisible. The pipe is buried under concrete, pavers, or soil -- sometimes many feet deep -- and the only surface evidence is a pool that keeps losing water. Pipe testing is the systematic, non-destructive method for confirming whether a buried pipe has a break and identifying exactly which line is responsible.
Rubber test plugs -- sized to fit each pool fitting precisely -- are inserted into the return jets, skimmer inlets, main drain, and cleaner port at the pool. This seals each line at the pool end, isolating the underground section of pipe between the pool and the equipment pad from the pool water itself.
A pressure manifold connects to the plumbing system at the pump and filter equipment. The manifold has individual ports for each line and a pressure gauge, allowing the technician to pressurize one line at a time while keeping the others isolated. This is the control center for the test.
Air is introduced into one line at a time through the manifold at a controlled, moderate pressure -- within the safe operating range for the pool's PVC plumbing. The line fills with air from the equipment pad through the buried pipe to the sealed plug at the pool end.
With the line pressurized, the technician watches the gauge and waits. An intact line holds its pressure -- the needle stays steady. A broken line loses pressure as air escapes through the crack or failed joint underground -- the needle drops. The rate and pattern of the drop provides additional diagnostic information about the size and nature of the break.
Each line is tested in sequence and the result recorded. Every line gets documented -- not just the ones that fail. This creates a complete picture of the pool's plumbing condition and ensures that multiple breaks in different lines aren't missed.
Any line that failed is then re-pressurized with trace gas (5% hydrogen / 95% nitrogen blend). The gas travels through the pipe and escapes at the point of the break, rising through soil and concrete to the surface. A surface sensor detects the hydrogen, and the technician marks the exact location of the break. This is what allows targeted excavation -- not exploratory digging.
Air is used as the testing medium for two specific reasons. First, air compresses -- which means pressure changes register immediately on a gauge. Water is incompressible, making it much harder to detect small, gradual pressure losses from hairline cracks. Second, air is the carrier needed for trace gas. After a line fails its air test, trace gas is introduced into the same pressurized air column. If water were used, the trace gas can't flow through the line to reach the break.
See how your pool's water loss pattern compares to evaporation -- and whether underground plumbing could be the source.
Leak and Subsurface Locators tests each pool plumbing line individually -- so there are no surprises after the concrete is cut. Call Sandra to schedule.
When done correctly, no. Testing pressure is kept within safe operating levels for standard pool PVC plumbing. The concern with old or brittle plumbing is over-pressurization -- something that doesn't happen with a properly trained technician using a calibrated manifold. If a line is already so degraded that normal test pressure causes a failure, that failure was already happening under normal pump pressure anyway.
This is rare with properly performed testing, but it can happen if plugs weren't sealed correctly, if there's a slow leak that wasn't monitored long enough, or if the break is at a joint that reseats under different pressure conditions. This is one reason why trace gas location after a failed test is important -- it provides independent confirmation of where the break is before excavation begins.
No. Pool plumbing can be tested with the pool full. The plugs are inserted at the pool fittings by a technician who enters the water, sealing the lines from the pool side. The pool level does not need to be adjusted for the test to be accurate.
A standard residential pool typically has four to seven plumbing lines: one or two suction lines (skimmer and main drain), two to four return lines, and a cleaner line. Pools with spas add additional lines -- spa returns, blower lines, and spillway connections. Each line is tested individually, so the total number of tests depends on the pool's configuration.