For more help with this issue, see acoustic leak detection: how listening gear finds leaks, pressure testing your plumbing, our emergency leak detection overview, and thermal imaging for hidden leaks.
Hidden Wall Pipe Bursts
A supply pipe inside a wall can split and spray into the cavity for hours before water shows on the surface. By the time stains appear, insulation and drywall are saturated. Acoustic listening hears the spray through the wall and marks the exact spot.