As part of ongoing efforts to maintain the infrastructure, and as an integral part of a multi-barrier approach to protecting and enhancing the quality and safety of our drinking water, the Resort Municipality of Whistler (RMOW) conducted a comprehensive water line flushing program annually from May to October.
Flushing is a process that rapidly removes water from the piping system, similar to the process of flushing a car's radiator. Flushing uses water velocity to scour out materials that accumulate in the municipality's pipes.
Water pipes are usually flushed by opening fire hydrants, where the discharged water is directed through a specially built trailer, designed to remove disinfection chlorine and control the flow of water to reduce erosion. The RMOW uses a procedure known as unidirectional flushing, which is superior to traditional flushing techniques because it allows crews to direct the flow of water and isolate specific sections of pipe, creating more efficient scouring and using less water.
Why is flushing needed?
Imagine driving down the road at less than two kilometers per hour. That's about the rate that water moves through underground pipes. This slow movement causes sediment like rust and mineral particles to build up over time and accumulate along the pipe's bottom. A buildup of bacteria known as "biofilm" can also coat the pipe's inner surface. This combination of sediment and bacteria can restrict water flow in the pipes and contribute to the pipe corroding. Rapid water pressure changes, such as water main breaks and the use of fire hydrants, can stir up the sediment and dislodge deposits lining the pipe, resulting in "dirty water" appearance.
Periodically flushing of water pipes removes the sediment and biofilm buildup, thereby maintaining the RMOW’s infrastructure and assuring consistent good quality water.
Is flushing a waste of water?
RMOW staff follow procedures when flushing that minimize the amount of water used. Areas with little sediment are flushed only briefly.
How will this affect me?
Usually, you will not be aware that flushing is taking place in your neighborhood. Flushing generally is conducted between 8 a.m. and 4 p.m. Monday through Friday, and takes about 30 minutes to flush each hydrant. While the hydrant is being flushed, the homes on that block may experience discoloured water or a drop in water pressure. You should limit or avoid using water during the times when crews are flushing in your area, and do not use coloured water for purposes that require clean water, such as food preparation, medical or dental procedures and laundry.
Creating high velocity within the water pipes has the potential to create backsiphonageback flow.
Commercial businesses, such as laundromats, beauty salons, spas, restaurants and hotels, may contact the RMOW Environmental Operations Department at 604-935-8300 for further details and advance warning of flushing in their areas.
The RMOW has considered flushing in the middle of the night to minimize customer inconvenience. However, flushing during daylight hours reduces the RMOW’s labour expenses and allows for easier identification when locating valves and hydrants.
If you experience no water pressure after crews have finished flushing in your area, please contact the RMOW Infrastructure Department at 604-935-8300 or, for emergencies and after hours, at 604-935-8320.
What should I do if I see discoloured water coming out of my faucet?
Should a reddish, yellow, or brown tint to the water appear, do not be alarmed. It is recommended you do not use the water or do laundry for about two hours. This will give the sediment time to settle. After two hours, run a cold faucet for about five minutes to make sure the water is clear. Do not choose a faucet with a water filter connected to it, as sediment may clog the filter. Do not use a hot water tap as doing so may draw sediment into your hot water tank.
If the water does not clear within a couple of hours, call 604-935-8300.
What if someone accidentally drinks coloured water?
Drinking discoloured water should not make you sick or have adverse health effects. However, it may not smell, look or taste very good.
Will flushing affect the natural environment?
The RMOW takes all precautions to protect the environment and maintain water quality. A de-chlorination trailer is used to remove disinfection chemicals and control the high flow and volume of discharge water, minimizing erosion and effects on natural water courses. During the flushing operation, crews continually monitor the chlorine and turbidity levels of the discharged water. Unidirectional flushing actually reduces the collective impact on the natural environment because it results in less disinfection chemicals being used, increases distribution efficiency, water savings over traditional flushing methods and reduces overall water use.
Why aren’t crews flushing in my area?
In the RMOW, many areas have privately owned water mains and hydrants. These lines and fixtures remain the responsibility of the owners, and the RMOW does not conduct water main flushing on private water lines or hydrants.
Are there other cities that do water main flushing?
Many cities across North America use unidirectional flushing as a regular part of their maintenance programs. This is considered the best method for cleaning water mains and improving distribution reliability.
