The fire department said it was notified of the accident at a farm in the nearby municipality of Durrenroth shortly after 7am.
Local fire fighters were struggling to deal with the situation.
The cows had fallen into the tank from a narrow opening in the barn, the Bern fire department said.
The animals had to be removed from the same small opening making the rescue a challenge, the department said.
High-intensity fans were used to aerate the cesspool while two fire fighters, equipped with special suits and berating apparatus, jumped into the muck.
They then attached harnesses to the cows to remove them from the tank unharmed.
Members of the Langenthal and Durrenroth fire departments were involved in the rescue along with a veterinarian.