What is uni-directional flushing?
During uni-directional flushing, water system valves are operated to create one-way flow to isolate a section of water main to be cleaned. A hydrant connected to the main is then opened to remove the built-up sediment. This type of flushing increases the speed of the water flow in the main to about two metres or six feet per second (it is normally less than .3 metres or 1 foot per second). This high speed produces a scouring action in the mains, removing sediment deposits. The flushing starts at a clean water source (e.g., the water pumping stations) and moves through the water main system. This ensures that clean water is always used to flush the mains.
