Water quality, water hardness and water data

We take the responsibility of providing clean, safe water to Calgarians very seriously. Conversely, we must also ensure that the water returning to our rivers, via our stormwater or our wastewater, is equally clean and safe.

The City’s subject matter experts in Water Quality & Regulatory Assurance support all aspects of water within Calgary. Together we work to protect public health, infrastructure and our environment by monitoring, testing and tracking water quality data, trends and environmental performance. The City has four four externally accredited laboratories that maintain the ISO 17025 standard (through CALA) – providing confidence to Calgarians about the quality and safety of our water.

	2019	2020	2021	2022	2023
Number of tests completed for drinking water line of service	112489	112819	127136	142206	137456

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Water hardness

Calgary's water is considered hard because of the amount of calcium and magnesium in the water from the Bow and Elbow Rivers.

What is water hardness?

Water hardness is caused by calcium and magnesium in the ground and surface water. These minerals come from rock such as limestone that dissolves in our river system. The results of having hard water can include difficulty making lather or suds while washing and/or a build-up of minerals on taps and other fixtures.

How hard is Calgary's water?

The hardness of Calgary's water varies seasonally and by location:

The Bow and Elbow Rivers each have different hardness levels
The lowest hardness levels are typically during spring snowmelt and the highest hardness levels are between December and February.

Generally, people in the northern half of the city receive water from the Bow River through the Bearspaw Water Treatment Plant. Residents in the south receive most of their water from the Elbow River through the Glenmore Water Treatment Plant.

Water Hardness, mg/L CaCO₃

	December to February	March to May	June to September	October to December
Bearspaw range	184-198	140-186	126-159	144-173
Glenmore range	248-262	181-256	182-213	187-220

*ranges for 2023

Are there health issues with water hardness?

There are no known health effects associated with calcium and magnesium minerals in drinking water. However, conventional water softening systems (those that use salts) may not be suitable for people on sodium-reduced diets.

We recommend that consumers thoroughly research the various water softener systems available before deciding whether or not to soften their water.

For more information on water hardness please see the Canadian drinking water quality guidelines.

Water Quality Summaries

Treated Water from the Treatment Plants.

Key Drinking Water Quality Parameters 2023

Basic Water Chemistry

Water Quality Parameter	Units	Drinking Water Results	Limit	Major Source
Color	TCU	<2	≤15^a	Erosion of natural deposits in watershed.
Hardness as CaCO₃	mg/L	126 - 262	No limit	Erosion of natural deposits in watershed.
pH	pH Units	7.3 – 7.8	7.0-10.5^b	Influenced by the dissolved minerals in the water, temperature, and water treatment processes.
Temperature	°C	1.1 – 22.0	≤15°C^a	River water temperature.
Total dissolved solids	mg/L	155 - 334	≤500^a	Erosion of natural deposits in watershed.
Turbidity	NTU	<0.05 – 0.09	<1.0	Suspended particles in water.

Inorganic Substances

Water Quality Parameter	Units	Drinking Water Results	Limit	Major Source
Aluminum	mg/L	0.010 – 0.124	0.1^{b, c}	Water treatment process
Arsenic	mg/L	<0.0005	0.01	Erosion of natural deposits in watershed.
Barium	mg/L	0.026 – 0.083	2.0	Erosion of natural deposits in watershed.
Cadmium	mg/L	<0.0005	0.007	Erosion of natural deposits in watershed.
Calcium	mg/L	32 - 69	No limit	Erosion of natural deposits in watershed.
Chlorine residual, free	mg/L	0.85 – 1.33	≥0.2	Plant treatment.
Chromium	mg/L	<0.0005-0.006	0.05	Erosion of natural deposits in watershed.
Copper	mg/L	<0.0005 - 0.0006	≤ 2 ≤1^a	Erosion of natural deposits in watershed. Leaching may occur from plumbing (pipes and brass fittings).
Fluoride	mg/L	0.09 – 0.28	1.5	Naturally occurring.
Iron	mg/L	<0.010 – 0.017	≤0.3^a	Erosion of natural deposits in watershed.
Lead	mg/L	<0.0005	0.005	Erosion of natural deposits in watershed. Leaching may occur from plumbing (pipes, solders, and brass fittings).
Magnesium	mg/L	11 - 22	No limit	Erosion of natural deposits in watershed.
Manganese	mg/L	<0.0005 -0.0012	≤0.12 ≤0.02^a	Erosion of natural deposits in watershed.
Mercury	mg/L	<0.0000019	0.001	Erosion of natural deposits in watershed.
Nickel	mg/L	<0.0005 -0.0006	No limit	Erosion of natural deposits in watershed. Leaching may occur from plumbing (pipes, solders, and brass fittings)
Nitrate as Nitrogen	mg/L	<0.005 – 0.19	10	Erosion of natural deposits in watershed.
Nitrite as Nitrogen	mg/L	<0.005	1	Erosion of natural deposits in watershed.
Potassium	mg/L	0.4 - 1.1	No limit	Erosion of natural deposits in watershed.
Sodium	mg/L	3.4 – 16.7	≤200^a	Erosion of natural deposits in watershed.
Sulfate	mg/L	43 – 92	≤500^a	Erosion of natural deposits in watershed.
Zinc	mg/L	<0.0030 -0.017	≤5.0^a	Erosion of natural deposits in watershed. Leaching may occur from galvanized pipes, hot water tanks and brass fittings.

Microbiological Parameters

Water Quality Parameter	Units	Drinking Water Results	Limit	Major Source
E. coli	MPN/100 mL	<1	0	Domestic animals, wildlife and human waste.
Total Coliform	MPN/100 mL	<1	0	Soil, domestic animals and wildlife.

Limit specified by Guidelines for Canadian Drinking Water Quality (Health Canada Sept. 2022) or Alberta Government operating approval for aesthetic, health, and operational rationale.

TCU = True Colour Units.

NTU = Nephelometric Turbidity Units, a measure of water clarity.

MPN = Most-Probable Number.

mg/L = milligrams per litre, or parts per million (ppm)

(a) Aesthetic objective

(b) Limit based on annual average