01
Watch for a pattern, not one mark
A stain that grows after a fixture is used, a sound that continues when the home is quiet, or repeated dampness in the same path is more informative than one old mark.
Condensation, roof water, foundation moisture, and plumbing can overlap. Record timing and weather before assigning the source.
02
Compare use with the symptom
Note whether the sign changes after a shower, dishwasher cycle, toilet flush, heating call, or period of no use. A safe meter observation can also help frame a suspected continuous supply leak where the utility permits it.
03
Plan access in stages
Start with accessible valves, fixtures, ceilings, and service spaces. Open finishes only when the evidence supports the location and the access will change the repair decision.