The alert was sounded at around 7am when the cow tumbled into the tank on a farm in Dürrenroth, 30 kilometres northeast of the city of Bern.
Members of the Dürrenroth fire department arrived first at the scene and installed ventilation fans to blow away noxious gases from the sewage, the Berner Zeitung newspaper reported on its website.
This allowed firemen to safely attend to the messy work of attaching a harness to the animal so that it could be winched out.
Reinforcements arrived from the Bern Fire Department.
The cow had apparently fallen into the septic tank after a piece of grating had moved out of place.
That left the firemen with the challenge of lifting the cow through a narrow shaft opening of 52 by 71 centimetres, according to the Bern fire department.
A crane truck was used to extricate the burly animal from the place where it was trapped in an operation that took about an hour, the Berner Zeitung said.
No sooner had the rescuers started to wash down the exhausted cow with warm water and straw than it got up and appeared none the worse for wear, the newspaper reported.
A veterinarian on hand affirmed that the cow had escaped injury.
In addition to the vet, the rescue operation involved a total of 18 fire fighters.