From the rivers to your tap: How The City fills your water glass
Calgary’s roots are at the confluence of the Bow and Elbow rivers. The Blackfoot called it Moh’kins’tsis – the place where two rivers meet. These rivers have been an important part of life for thousands of years and making sure there is enough high-quality water flowing through these rivers remains vital for Calgary, upstream and downstream communities, and the fish and wildlife that call these waterways home.
“Maintaining a healthy watershed is important for Calgary, as well as the broader region,” said Francois Bouchart, Director of Water Resources – Planning. “It is the first, foundational piece in providing safe drinking water to Calgarians.” Bouchart goes on to explain that The City draws from both of Calgary’s rivers and then onto two water treatment plants.
The first, located in the city’s northwest, is Bearspaw Treatment Plant. Drawing its water from the Bow, it takes approximately 11 hours to complete the water treatment process. Over at the Glenmore Water Treatment Plant, water is drawn from the Elbow. The production rate and entire water treatment process here takes approximately 15 hours.
Together, these plants can produce a combined total of 950 megalitres of drinking water per day - enough to fill the Calgary Saddledome nearly three times!
Our operations work 24 hours a day, 365 days a year to provide Calgarians high quality, safe drinking water. We are diligent every step of the way and are proud to provide a refreshing glass of water at the low cost of just .04 of a cent.
How does it all work?
Watersheds and intake
The Bow and Elbow rivers 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. This raw water is collected by intake pipes and flows through coarse screens to remove large debris before going to the pre-treatment facility at the plants.
The pre-treatment facility uses a process known as "flocculation" to capture and remove sediment, debris and micro-organisms from the raw water supply. Raw water then enters large mixing tanks where aluminum sulphate, sand and polymer are added, attaching to the particles in the water creating what is known as “floc.” This makes particles heavy, causing them to settle to the bottom of the tanks.
Clarified water at the surface continues on to the next stage of treatment, while dirty water at the bottom of the tanks is pumped to the residuals treatment facility. By the time water moves out of this treatment phase, more than 99 per cent of silt and debris has already been removed.
Clarified water enters the clarified water basin, where a small dose of sodium hypochlorite (chlorine) is added, this also makes other contaminants in the water easier to remove during the next treatment steps. The clarified water basin provides enough time to disinfect the drinking water, killing micro-organisms and viruses that can cause disease.
As water is being treated, the 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 collected and dried before being sent to City landfills.
The residuals treatment facility reduces The City's operational impact on the environment in two ways:
- By sending silt and debris to the landfill instead of back into our rivers, it greatly benefits our aquatic ecosystem.
- 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 sediment, 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. The water then flows to the onsite storage reservoir.
Onsite Storage Reservoir
The onsite reservoir helps to maintain a steady flow through the plant and allows for sufficient contact time with the sodium hypochlorite (chlorine) to make sure the treated water has been completely disinfected before it is pumped to the distribution system.
Before the water is pumped off-site, one final dose of chlorine is added in a process called post-chlorination. This ensures the water remains drinkable on its journey through nearly 5,000 km of pipe to Calgary homes and businesses.
High-pressure pumps, or pump stations, are located throughout Calgary and move the water from the treatment plants through the drinking water distribution system. The pumps push large volumes of water through large pipes called transmission mains to strategically-located water storage reservoirs, other pump stations, and smaller distribution networks.
A group of professional chemists, microbiologists and aquatic biologists staff the water quality laboratories in both treatment plants checking the water quality along the way. This team continuously monitors the quality of the source water that enters both the Glenmore and Bearspaw Treatment Plants, at every stage of the treatment process and throughout Calgary’s water distribution system. This provides The City with important information about the quality of the water before it is treated and helps determine the adjustment levels of treatment to produce safe drinking water.
“Our operations work 24 hours a day, 365 days a year to provide Calgarians high quality, safe drinking water. We are diligent every step of the way and are proud to provide a refreshing glass of water at the low cost of just .04 of a cent,” said Dan Limacher, Director of Water Services.
To take an online tour for yourself or to join our water educators on a fun, informative and interactive tour of one of our water treatment plants, visit calgary.ca/watertours.
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