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Metro Vancouver - About Your Water

April 11, 2023 4 min read

About Your Tap Water, Where it Comes From, How it’s Treated

Tap water in Metro Vancouver comes from rain water and snow melt collected in three huge reservoirs in the North Shore Mountains and the Coquitlam watershed. These mountain reservoirs are the source of our drinking water in Vancouver and the surrounding municipalities that make up Metro Vancouver. The Capilano, Seymour and Coquitlam reservoirs are remote, protected and upstream from human activity. They are free from human effluent, with no contamination from industry, agriculture or pharmaceuticals. These are enviable source water conditions compared to the contaminated, post-use sources from which most other municipalities around the world get their drinking water today. Mountain water is collected and stored in these huge reservoirs. This is called ‘raw’ water. Each reservoir supplies approximately one third of Metro Vancouver’s water. Water from the Capilano and Seymour reservoirs is treated at the Seymour-Capilano Filtration Plant. Water from the Coquitlam reservoir is treated at the Coquitlam Drinking Water Treatment Plant.

This entire regional water source and treatment process is administered by Metro Vancouver which distributes the treated water to your local municipality. Your municipality is responsible for distributing this treated water to your tap.

The population of Metro Vancouver is approaching
2.5 million. We use a billion litres of tap water a day.
Metro Vancouver and our local municipalities are required to ensure that our tap water meets standards established by Health Canada and provincial health authorities. Since the year 2000 significant expenditures have been made to upgrade the treatment and distribution of drinking water in the Metro Vancouver region.

What Happens to Water Before It Gets to Your Tap?

Each reservoir has geological characteristics that influence the method of treatment required. For this reason the treatment methods applied at the Seymour-Capilano Filtration Plant are not the same as those applied at the Coquitlam Water Treatment Plant


Seymour-Capilano Filtration Plant (SCFP)

Raw water from the Capilano and Seymour reservoirs are treated at the SCFP.

  • Filtration is used to remove particulates, organic matters and micro-organisms.
  • The filtration process is chemically assisted with the use of alum or poly aluminum chloride which coagulates and clusters particles for more efficient removal.
  • These clustered particles and the coagulant are removed by filtering the water through anthracite and sand. 
  • The filtered water is then disinfected by exposure to UV (ultra violet light). 
  • To prevent corrosion in the water distribution system, the water pH is raised to approximately pH 7.5 by the addition of lime and CO2
  • Chlorine (sodium hypochlorite) is added to the water before it goes into the distribution system. 

The Seymour reservoirsupplies water to eastern Burnaby, South Surrey and western New Westminster.

Twin Tunnels

Huge tunnels, each 7.1km in length, have been bored through the base of Grouse Mountain and Mount Fromm. One tunnel transports raw water from the Capilano Reservoir for treatment at the Seymour-Capilano Filtration Plant. After treatment the other tunnel transports filtered water back to Capilano for distribution.

The Capilano reservoir supplies water to western North Vancouver, Vancouver, Richmond and western Burnaby.

Coquitlam Water Treatment Plant

Raw water from the Coquitlam reservoir is treated at the Coquitlam Water Treatment Plant.
The geology of the Coquitlam watershed is different from the Capilano and Seymour watersheds.
Filtration is not required at the CWTP due to the clearer characteristics of the raw water in the Coquitlam reservoir.

  • Water is pre-treated with ozone. 
  • Water then gets exposed to ultra violet light (primary disinfection method) at the Coquitlam UV Disinfection Facility.
  • Soda ash is added to raise water pH to approximately 7.5. 
  • Chlorine (sodium hypochlorite)is added before the finished water leaves the treatment plant to prevent bacterial regrowth in the water distribution system.
  • Cryptosporidium & Giardia cysts continue to be a challenge for the Coquitlam treatment process.


The Coquitlam reservoir supplies water to Port Coquitlam, Pitt Meadows, Maple Ridge, Langley, eastern New Westminster and Coquitlam.

Gravity Saves on Pumping Costs

Because our water reservoirs are located in mountainous areas, gravity is the natural and most cost effective means to shunt water downhill to our municipalities. In the event of an emergency or if water supply or quality were to become compromised in one reservoir, cross-pumping can transport water from another reservoir to any part of the system. 





Metro Vancouver supplies water to:

Bowen Island
Electoral Area A
Langley Township
Maple Ridge
New Westminster
North Vancouver
North Vancouver District
Pitt Meadows
Port Coquitlam
Port Moody
Tsawwassen First Nation
West Vancouver

Image source:

Metro Vancouver -

  1. a geographical area in British Columbia’s lower mainland comprising 21 municipalities, one Electoral Area and one First Nation.
  2. a political and corporate entity, also known as a regional district, that administers essential services to the cluster of communities loosely identified by the same name.

Watershed - a mountainous area defined by slopes that funnel the descent of creeks and rivers into a common valley. 

Reservoir - a containment area where water is collected from the surrounding mountains and stored before distribution to our communities. Capilano, Seymour and Coquitlam are huge natural reservoirs


What Makes Our Tap Water Different?

The Source

  • Protected natural mountain sources.
  • First use. Not recycled waste water.
  • Not downstream from human activity or effluent. 

Unique Characteristics 

  • Very soft water
  • Low alkalinity and mineral content. 
  • pH is naturally low and adjusted to approximately pH 7.5 to prevent corrosion.
  • No contamination from industry, agriculture, pharmaceuticals. 

Local Infrastructure for Water Treatment & Distribution

  • World class water treatment plants.
  • Investment in maintenance & upgrades to infrastructure.
  • Planning for the future: population growth & climate change

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