Drinking Water Treatment Processes

Metro Vancouver treats your drinking water in two stages. First it is treated at the source (where it comes from). It is given additional (secondary) treatment where required as it travels throughout our region. This ensures that your drinking water is safe and clean when it reaches your home or businesses, even if you live far away from the original source.

Treatment at the Source

Our drinking water is treated right as it leaves the source reservoir to ensure it meets regulatory standards. Each drinking water treatment plant is designed specifically to treat the water coming from its corresponding reservoir. Read more about the facilities at the Seymour and Coquitlam Reservoirs here.

Filtration at the Seymour-Capilano Filtration Plant (SCFP)

Filtration improves drinking water by removing particulates, organic matter and micro-organisms. An added benefit of filtration is that less chlorine is required to maintain water quality in the distribution system. This facility also uses UV disinfection.

Disinfection with Ozone, UV and Chlorine at the Coquitlam Water Treatment Plant (CWTP)

There are natural particles and microorganisms in any water source. Even at low levels we manage for these risks using a combination of ozone and ultra violet (UV) light and chlorine to inactivate any micro-organisms present in the source water.

pH Adjustment

Our water, by nature’s design, has a low pH, alkalinity and mineral content. That means it is very soft water. To adjust the pH level we add lime (calcium hydroxide) or sodium carbonate. These additives in no way impact the flavour or safety of our drinking water.

The primary treatment process at the Seymour-Capilano Filtration Plant (SCFP) is filtration, and then UV and chlorine (this facility treats water from both the Capilano and Seymour Reservoirs).

The primary treatment process at the Coquitlam Water Treatment Plant is UV, and then ozone and chlorine.

Treatment through the System

As water flows through the distribution system, the chlorine added during the primary treatment stage gradually breaks down, creating the potential for bacteria. If required, chlorine is added as a secondary disinfectant to preserve water quality as water travels to homes, businesses, and industries. Chlorine lasts long enough to treat the water, making it ideal for this purpose. Ozone and UV light are not suitable because they are either stationary (UV) or dissipate very quickly (ozone).

Why is chlorine chosen for secondary disinfection? Because it is extremely effective and stays in the water until it reaches its destination. Ozone breaks down too quickly, and UV treatment doesn’t last long enough. Secondary treatment ensures water continues to meet Health Canada’s standards as it travels through water mains across the region.

The Drinking Water Management Plan published in 2011 explains the direction and priorities for drinking water in this region. Find out more about how your drinking water is treated, and current priorities, on page ten.

Common Queries about your Drinking Water

Chlorine and odours

Some homes are closer to the rechlorination stations, and the odour can be stronger as water comes direct from the tap. Some residents are more sensitive to the odour from the chlorine added in the water treatment process. Chlorine is a gas, and it leaves the water quickly when exposed to air. Try this yourself - put a jug of tap water in the fridge to keep cold. You should notice that any chlorine odour is gone very quickly.

Our water is soft

Our water source is rain (and snow) and it doesn’t spend a lot of time stored in rocks so has a low mineral content. Cities with hard water usually source their water from rivers that have a lot of minerals, or have granite ground water reservoirs.

For bathing and washing, soft water means that a little soap goes a long way. But not everyone realizes that. And as a result, residents tend to use more soap than necessary. The good news is you can get clean, save money on soap and help the environment by using less. Read more.

Is Fluoride added to our drinking water?

No fluoride it is not added. There is a natural level of less than 0.05mg/ L. Fluoride drops can be purchased over the counter at a drug store.