Flushing systems Flushing systems are basically made up by a Sanitary Bowl and its Hydraulic Flushing Device used to release the water that cleans the bowl from waste products. Hydraulic Flushing Devices are a flushing valve, a coupled cistern, or a suspended tank. Waste pipe and its ventilation, too, are part of the system. All components need to work together perfectly to obtain a flawless performance.