Maintenance workers investigating a blocked sewer discovered the cause was several hundred €50 notes.
The notes, torn into strips and floating in sewage were flushed out with a high pressure hose by a team from company Veolia.
The incident occurred in the Quatre-Saisons area of Aveyron in the Midi-Pyrénées.
According to La Depêche the maintenance crew called the police who have started an investigation.
The final sum of the flushed notes has not been released.