The float called for pumping
Water level and run signal increased together.
↓House Autopsy · site-water-and-drainage
The sump pump that hummed but did not move water
The motor energized while a failed impeller and blocked discharge prevented useful flow.
Trigger conditionrising groundwater
Four layers, one connected story.
Electrical operation created a steady hum
Sound confirmed power but not water movement.
↓The discharge remained inactive
A blocked path or damaged impeller separated sound from performance.
↓Flow observation and component inspection found the failure
The replacement was verified during a controlled water test.
Canonical connection
The symptom and cause are separate objects.
The autopsy preserves how evidence connected them without collapsing uncertainty into one magic answer.
The motor energized while a failed impeller and blocked discharge prevented useful flow.
The visible symptom was the final chapter
The investigation followed the source, transport path, affected material and verification step separately.
What changed the direction
Timing and location evidence ruled out attractive but weaker explanations before repair work began.
The durable lesson
Repair the controlling source and then verify the outcome under the conditions that previously triggered the symptom.
Source→Path→Damage→Verify
