Abstract: A flood stopper system is used to prevent movement of fluid from a floor drain system out onto a floor that is being cleared by that drain system. The flood stopper system includes a balloon-like inflatable element that is automatically inflated to occlude the drain system in the event of a flood situation. The stopper system is located in the drain in a stand-by configuration and includes a float that covers a fluid-sensor and is only moved when a potential flood situation is present. Movement of the float permits fluid to contact the sensor and upon such contact, the sensor generates a signal that is used to fluidically connect a source of pressurized gas to the inflatable element to occlude the drain system.