Abstract: In a drainage system for maintaining a swimming pool cover drained of accumulated precipitation, a pump with its intake is disposed in a fluid trap defined by an upper surface of the swimming pool cover. A discharge port of the pump is disposed outside of the fluid trap. A sensor is disposed in a flow path of the pump for detecting the presence of fluid flow therethrough, while a clock unit is operatively connected to the pump for periodically operating the pump for a ten-second interval. A control circuit continues to operate the pump beyond the ten-second interval upon the detection by the sensor of fluid flow through the pump at the end of the ten-second interval. In that case, operation of the pump is terminated only upon a cease of fluid flow through the pump.