Annual Unidirectional Flushing Program

What is Unidirectional Flushing? 

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

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, removes turbidity and restores flow in the water distribution system.

What are the Benefits of Unidirectional Flushing? 

The benefits are improving water 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 on February 19, 2024, Monday to Friday, 8:00 am to 5:00 pm and can take up to 8 weeks to complete. 

Will Residents Be Affected?

Please be advised that 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 watermains. 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 45 minutes. Then flush from your bathtub tap or outside tap until the water runs clear.