A septic odor can come from more than one source, including normal venting or a system problem, so context matters.
Check for accompanying symptoms
Backups, slow drains, wet areas near the tank or drainfield, or persistent sewage odors deserve professional attention. EPA notes that odors alone do not always mean system failure.
Take persistent warning signs seriously
If an odor is persistent or appears with other symptoms, investigate the cause rather than relying on a deodorizing treatment.
Useful next reads: maintenance guide · warning signs · septic additives evidence