Following violent rainstorms, the runoff water in an industrial zone could no longer flow into a mud-clogged pipeline serving a pharmaceutical plant. The arrival of water caused the retention tank of the site to overflow, thereby flooding the fire premises located in an underground pit. As a safety precaution, the water triggered the start of the motor pump (whose motor was damaged by the entry of air), that activated the water and foam networks of the storage buildings. To reduce the chances of recurrence of such an accident the operator has elevated the entry point of the fire premises, ensured surveillance of the storm drains and carried out maintenance of existing structures.