Flushing the watermains improves water quality by removing sediment that slowly build up at the bottom of the watermain over time.

During uni-directional flushing, water system valves are operated to create one-way flow to isolate a section of water main to be cleaned. A hydrant connected to the main is then opened to remove the built-up sediment. This type of flushing increases the speed of the water flow in the main to about two metres or six feet per second (it is normally less than .3 metres or 1 foot per second). This high speed produces a scouring action in the mains, removing sediment deposits. The flushing starts at a clean water source (e.g., the water pumping stations) and moves through the watermain system. This ensures that clean water is always used to flush the mains.

Typically early Spring and Fall. We avoid excessive water consumption during the Summer months.

The City will inform residents before starting the flushing program by posting notices on our website and placing advertisements in local newspapers. You’ll also see orange signs in neighbourhoods where flushing is taking place.

Flushing may cause short-term pressure fluctuations along with discolouration and sediment in the water reaching your home or business.

When you see flushing being carried out on your street, you should avoid using your hot water system to minimize the amount of sediment drawn into your hot water tank.

Drinking discoloured water should not make you sick, however, it may smell, taste, or look unpleasant.

Immediately after cleaning, you may notice that your water is cloudy or has a chlorine smell.

Cloudy water
Water is cloudy when air gets in it and makes tiny bubbles. These bubbles are harmless and will disappear if you let the water sit for a few minutes.

Chlorine smell
We add enough chlorine to the water to keep it safe. You can easily get rid of the chlorine taste and smell by filling a container with water and keeping it in the fridge for drinking – much of the chlorine will leave the water overnight.

The Greater Vancouver Regional District monitors the water quality by sampling and testing at water sampling stations throughout the City on a weekly basis to ensure that the water in the water distribution system is safe to drink.

In addition to removing more sediment and using less water than conventional flushing, watermain flushing tests and exercises the water system valves and hydrants.

Many cities have some type of flushing program to clean their watermains (e.g., conventional flushing or unidirectional flushing). This is considered the best way to improve water quality and increase the reliability of the water distribution system.