Pressure Testing for Leak Detection

Isolate a section of pipe, bring it to a known pressure, and watch the gauge. A section that holds is intact. A section that falls is losing water somewhere along its length. This converts a vague symptom into a defined search area.

The result is binary and hard to argue with, which is why it is used both at the start of an investigation and at the end, to verify that a repair actually resolved the loss.

• Whole-house supply, to confirm continuous loss on the pressurized side
• Hot versus cold separation at the water heater, which halves the search area
• Individual branches and risers, to identify one section in a larger system
• Service line between meter and building
• Irrigation mainlines and zones
• Pool suction and return lines tested individually at the equipment pad

A rapid drop suggests a substantial opening; a slow bleed suggests a pinhole, a seeping fitting, or in some cases a valve that is not sealing completely. Small pressure movements can also come from thermal changes in the water, so a test is given enough time and context to be meaningful rather than read in the first thirty seconds.

Pressure testing proves that a section leaks. It does not say where along that section the leak is. That is why it pairs with acoustic and thermal work: one method narrows the system, the other narrows the spot.