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Water treatment online tour


Creating high-quality drinking water for over one million Calgarians

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The City strives to ensure all Calgarians have a safe and reliable supply of drinking water. Calgary's water treatment plants, Glenmore and Bearspaw, operate 24 hours a day, 365 days a year. Operators, electricians, maintenance, the laboratories and administrative employees all work together to ensure the integrity of our drinking water.

The plants can produce a combined total of 950 megalitres of drinking water per day, enough to fill the Calgary Saddledome nearly three times. We invite you to learn more about the processes, technologies and the professionals working behind the scenes to ensure over one million Calgarians have high-quality drinking water 24 hours a day, 365 days a year by clicking through the images.


The City draws its water from the Bow and Elbow Rivers, which are fed by ground and surface water (in the form of glacier melt, snow melt and rain) from the massive land area that makes up the watershed.

The Bearspaw Water Treatment Plant - located in Northwest Calgary, draws its water from the Bow River, while the Glenmore Water Treatment Plant located in the Southwest draws its water from the Elbow River.

Elbow River Watershed - The Elbow River is the source of nearly half the city's water supply. The Elbow River Watershed covers an area of 1,210 square kilometres and drains into the Glenmore Reservoir.

Bow River Watershed - The Bow River Watershed has an area of 7,770 square kilometres. The Bow River originates at the Bow Glacier north of Lake Louise. It supplies the Bearspaw Water Treatment Plant.

Why do we treat Calgary's water?

In the spring, following a rainstorm or snow melt, runoff flows across the ground and into the rivers. The runoff picks up and carries dirt, sediment and other contaminants, such as organic substances, into the river drainage system. Raw water quality varies naturally and requires water treatment to ensure that the water is safe for us to drink.


The Pre-Treatment Facility uses a process known as "flocculation" to capture and remove silt, debris and micro-organisms from the raw water supply. By the time water moves out of this treatment phase, more than 99 per cent of silt and debris has already been removed from your drinking water.

How are silt, debris and micro-organisms removed?

Raw water enters large mixing tanks where aluminum sulphate is added, which binds to the silt and debris in the raw water, creating what is known as "floc". Sand and polymer are introduced, which also binds to the floc, helping rapidly pull the floc down to the bottom of a settling tank.

Clarified water at the surface continues on to the next stage of treatment, the clarified water basin, while dirty water at the bottom of the tanks is pumped to the residuals treatment facility.


Clarified water enters the Clarified Water Basin, where a small dose of sodium hypochlorite (chlorine) is added. The Clarified Water Basin provides enough time to disinfect the drinking water, killing micro-organisms and viruses that can cause disease.

Why use chlorine to disinfect our drinking water?

Chlorine is a naturally existing element that has been used to disinfect drinking water for most of the 20th century. Chlorine also makes other contaminants in the water easier to remove during the next treatment steps.

Residual Removal

Silt and debris from the pre-treatment and filtration process is sent to the Residuals Treatment Facility. This part of the plant acts as a giant strainer, removing as much water from the silt and debris as possible before recycling the water back to the start of the pre-treatment process. Strained silt and debris is eventually collected and dried before being sent to The City landfills.

The Residuals Treatment Facility reduces The City's operational impact on the environment. By sending silt and debris to the landfill instead of back into our rivers, it greatly benefits our aquatic ecosystem. In addition, recycling water within the plant has allowed The City to reduce the amount of water withdrawn from the river system by up to 10 per cent.


The final step in removing any remaining silt, debris and micro-organisms from our drinking water is accomplished by filtration. A number of large filtration beds act like a giant coffee filter, allowing water to flow through one layer of crushed coal and crushed sand before moving to the Distribution System.

The smallest of particles get stuck in the small spaces between the individual particles of crushed coal and sand. To prevent the filters from becoming clogged with particles, the filter is cleaned every 60 hours by a process of backwashing. A large pump pushes clean drinking water backwards through the filter. The stuck particles are loosened and carried away to the Residuals Treatment Facility, leaving the filter clean again.

Onsite Storage Reservoir

The onsite reservoir is used to balance high water demands with plant production levels to help maintain stable treatment processes. It also used to alllow sufficient contact time with the sodium hypochlorite to ensure complete disinfection of treated water before it is pumped to the distribution system.


After the water is filtered, it is drinkable and can be sent across Calgary. Before the water is pumped off-site, another dose of chlorine is added in a process called post-chlorination. This ensures it remains drinkable on its journey through the distribution system to customer homes and businesses.

High-pressure pumps, move the water from Glenmore and Bearspaw to supply the city's distribution system. The pumps push water through large pipes called transmission mains, which transport large volumes to strategically-located water storage reservoirs and pump stations. The water is then transported to smaller distributions that are used to deliver water to customers and fire hydrants.


Professional chemists, microbiologists and aquatic biologists staff the water quality laboratories in both treatment plants. They continuously monitor the quality of the source water that enters both the Glenmore and Bearspaw Treatment Plants. This gives us important information about the quality of the water before it is treated and helps us adjust the level of treatment to produce safe drinking water.

What does the laboratory do?

The laboratory operates seven days a week, 365 days a year and analyzes samples for a wide range of parameters. The water samples are collected in the watershed (for early warning of changing river conditions); at every stage of the treatment process (to optimize treatment processes and meet regulatory requirements) and throughout Calgary's water distribution system (to ensure public health). When the quality of water changes or other unpredictable situations occur, staff increases the frequency of sample collection and analysis, and adds additional monitoring sites.

This level of monitoring ensures that our drinking water consistently meets all federal Health Canada guidelines and provincial standards set by Alberta Environment. The key water quality parameters are listed in the Water Quality Report.