Water Main Flushing


What is Unidirectional Flushing?

Unidirectional Flushing (UDF) is a method of cleaning the inside of water mains within the distribution system. This UDF technique allows high flow velocities of water by isolating certain sections of water mains. This higher velocity water flow allows for better scouring of the inside wall of the water mains.

The UDF program is completed by closing water valves in a specific manner to create water movement in one direction while opening fire hydrants at the end of that section. Maintaining this flushing sequence is important so that the water used during flushing remains clean.

Why Unidirectional Flushing?

Slow moving water in the distribution system allows sediment and bacterial growth to accumulate over time. These deposits can result in water quality problems and contribute to the corrosion of some of the water distribution system. UDF inactivates bacterial growth, increases disinfectant residual, improves colour and removes turbidity, and restores flow in the water distribution system.

What are the Benefits of Unidirectional Flushing?

The benefits are improving the quality, colour, and flow of clean water through the distribution system. A preventative maintenance program is also implemented on valves and hydrants in conjunction with the UDF program.

When Will Unidirectional Flushing Take Place?

The UDF program will begin March 30, 2021 Mondays to Fridays, 8:00 am to 5:00pm and can take up to 6-8 weeks to complete.

Will Residents Be Affected?

Water valves and fire hydrants near your residence may be used to discharge water onto the street for several minutes. There may be a slight drop in water pressure or a presence of discoloration from the minerals and sediments that are being flushed out of the water mains. Your water service should not be disrupted during the flushing process. If a discoloration is noticed in your water, please turn the tap off for 15 minutes; then flush from your bathtub tap or outside tap until the water runs clear.

For an updated schedule on when this work will occur, please visit mission.ca/UDF.