Unidirectional Flushing

Unidirectional Flushing is part of the City of Castlegar’s regular water system maintenance program. It helps ensure high water quality, removes sediment and deposits, and maintains the long-term integrity of our water distribution system.

Flushing typically occurs once a year and follows a planned sequence that allows water mains to be cleaned systematically from one end of the system to the other. Approximately one-third of the City’s water distribution system is flushed each year. The program complements “on-demand” flushing done in response to water quality test results or line repairs. The goal is to flush every watermain in the city at least once every three years. This proactive approach helps extend the life of water distribution infrastructure and supports the health and safety of the community.

Notice of Work

Residents will be notified before flushing occurs in their area through:

• Neighbourhood sandwich boards
• The City’s electronic message board at the entrance to the impacted neighbourhoods
• A letter or door hanger will be delivered to homes and properties affected

If you have questions about the flushing schedule or the program in general, please contact
Civic Works at 250-365-5979.

What is Unidirectional Flushing?

Unidirectional Flushing (UDF) involves opening and closing valves and hydrants in a specific sequence to create higher water velocities. This process removes sediment, biofilm, and other debris that can build up over time in water mains. Flushed water is treated with a dechlorinating agent before being released, ensuring it meets the Ministry of Environment guidelines for water entering streams or storm systems. UDF is more effective than conventional flushing and uses less water overall.

Why Does it Matter?

Maintaining the water system through UDF helps:

• Improve and maintain water quality
• Extend the life of water mains and infrastructure
• Identify malfunctioning valves and hydrants
• Reduce the need for unplanned maintenance and repairs

What Should Residents Expect?

During flushing in your area, you may notice:

• Lower water pressure during flushing
• Temporary changes in water clarity (discoloured or cloudy water)
• Short interruptions to water service (rare)

To minimize inconvenience:

• Avoid using tap water, doing laundry, or running dishwashers during flushing hours in your area
• The water remains safe but may be aesthetically unpleasant during and shortly after flushing

If discolouration is observed, turn the tap off for 45 minutes, then turn on the cold water tap from your bathtub or outside tap for 15 minutes or until the water runs clear. Should the problem persist, please contact Civic Works. If crews are not actively working in your area, there is no need to wait 45 minutes.

The water remains safe but may be aesthetically unpleasant during and shortly after flushing.