Where does our water come from?
The Bow River supplies the Bearspaw Water Treatment Plant and the Elbow River flows into the Glenmore Reservoir, which is the source of water for the Glenmore Water Treatment Plant.
The Bearspaw Plant primarily supplies water to the north of the city, while the Glenmore plant supplies the south. However, water is interconnected through large diameter transmission mains to ensure a reliable supply to all times.
We withdraw water according to demand and within the rules set out by Alberta Environment. We are careful not to exceed our licenses for daily and annual withdrawals and are also careful to maintain enough flow in the river systems to support other users of the water system. Almost all of the water that is removed from the Bow and Elbow Rivers for use in Calgary is returned to the Bow River system after treatment in Calgary's wastewater treatment plants.
Learn more in 
From the River to the Tap.
Learn more about how we treat your drinking water - Take the Water Treatment Tour.
The Elbow River Watershed
The Elbow River is the source for nearly one half of the city's water supply. The Elbow Valley watershed covers an area of 1,210 square kilometres and drains into the Glenmore Reservoir. The Elbow River is 120 kilometres long and passes through four sub-climates before it enters the Glenmore Reservoir. The Elbow River is the source of water for the Glenmore Water Treatment Plant.
We draw water from the Glenmore Reservoir in order to provide treated water to citizens, but we also play an important role in flood control for this region. The reservoir is maintained at a level, depending on the flow rate of the Elbow River, that minimizes the risk of flooding around the reservoir and downstream of the dam.
The Bow River Watershed
The Bow River watershed covers an area of 7,770 square kilometres. The Bow River originates on the Bow Glacier north of Lake Louise and is one the three main tributaries of the South Saskatchewan River. The Bow River supplies the Bearspaw Water Treatment Plant.
When the water arrives at the water treatment plants it is referred to as raw water-–water that has not yet been treated. Run-off occurs when water from melting snow or a rainstorm flows across the ground and down into the rivers. This run-off water carries dirt and other contaminants. Raw water quality varies naturally as a result of run-off and requires treatment to ensure that the water is safe to drink.
