Unidirectional Flushing (UDF) is a method of cleaning the water mainlines through a network of flushing sequences with the water being discharged from a fire hydrant. A UDF program involves closing valves in a specific sequence to create water movement in one direction while opening specific fire hydrants at the end of that sequence.
The UDF technique allows higher water flow velocities by isolating certain sections of water mains. The higher water velocity allows for better scouring of the pipes and will use 40% less water in the flushing process than conventional flushing methods. Flushing pipes at higher velocities will dislodge and remove mineral deposits and sediment that accumulate in the water mains.