Water quality, water hardness and water data

Flushing mains after repairs is essential

As part of federally and provincially legislated water quality requirements, The City is required to maintain water quality after completing repairs.

Flushing ensures high-quality drinking water and protects our water distribution system.
Flushing must occur after a water main is repaired so that any sediment and contaminants that may have entered the pipes are removed.

For safety reasons residents should keep a respectful distance from workers and allow them to focus on their work.

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 Water Quality and Regulatory Assurance (WQRA) division provides scientific, technical and regulatory services to the utility protecting the environment, public health and City infrastructure. The management and staff of WQRA are committed to high-quality professional practices through continual improvement ensuring the quality of its services and accuracy of the analytical testing.

The City of Calgary WQRA laboratories are accredited for those tests listed on the Scope of Testing through the Canadian Association for Laboratory Accreditation (CALA) to ensure we meet and maintain the requirements of the ISO/IEC 17025:2017(E). WQRA laboratories produce data of high quality through accurate and reliable testing. Calgarians can be assured that our water is safe and high quality.

	2020	2021	2022	2023	2024
Number of tests completed for drinking water line of service	112819	127136	142206	137456	171754

Looking for water quality data not provided on this page or in our Open Data?

Complete a Water Data service request

*External requests will require a Data sharing agreement.

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

	January to March	April to June	July to September	October to December
Bearspaw range	152-211	152-197	134-163	158-187
Glenmore range	207-290	172-220	174-202	200-238

*ranges for 2024

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 2024

Water Quality Parameter	Units	Drinking Water Results	Limit	Major Source
Color	CU	<2	≤15^a	Erosion of natural deposits in watershed.
Hardness as CaCO₃	mg/L	134 - 290	No limit	Erosion of natural deposits in watershed.
pH	pH Units	7.0 - 7.8	7.0-10.5^b	Influenced by the dissolved minerals in the water, temperature, and water treatment processes.
Temperature	°C	1.4 - 22.3	≤15°C^a	River water temperature.
Total dissolved solids	mg/L	184 - 326	≤500^a	Erosion of natural deposits in watershed.
Turbidity	NTU	<0.05 – 0.07	<1.0	Suspended particles in water.

Water Quality Parameter	Units	Drinking Water Results	Limit	Major Source
Aluminum	mg/L	0.022 - 0.152	0.1b,c	Water treatment process
Arsenic	mg/L	<0.0005	0.01	Erosion of natural deposits in watershed.
Barium	mg/L	0.031 – 0.080	2.0	Erosion of natural deposits in watershed.
Cadmium	mg/L	<0.00015	0.007	Erosion of natural deposits in watershed.
Calcium	mg/L	35 – 74	No limit	Erosion of natural deposits in watershed.
Chlorine residual, free	mg/L	0.80 – 1.87	≥0.2	Plant treatment.
Chromium	mg/L	<0.0005	0.05	Erosion of natural deposits in watershed.
Copper	mg/L	<0.0005 – 0.0128	≤ 2 ≤1a	Erosion of natural deposits in watershed. Leaching may occur from plumbing (pipes and brass fittings).
Fluoride	mg/L	0.07 – 0.27	1.5	Naturally occurring.
Iron	mg/L	<0.010	≤0.1a	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	11.3 – 25.9	No limit	Erosion of natural deposits in watershed.
Manganese	mg/L	<0.0005 – 0.0011	≤0.12 ≤0.02a	Erosion of natural deposits in watershed.
Mercury	mg/L	<0.0000019	0.001	Erosion of natural deposits in watershed.
Nickel	mg/L	<0.0005 – 0.0007	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 – 0.151	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 – 1.5	No limit	Erosion of natural deposits in watershed.
Sodium	mg/L	3.5 – 15.3	≤200a	Erosion of natural deposits in watershed.
Sulfate	mg/L	43 – 95	≤500a	Erosion of natural deposits in watershed.
Zinc	mg/L	<0.003 – 0.013	≤5.0a	Erosion of natural deposits in watershed. Leaching may occur from galvanized pipes, hot water tanks and brass fittings.

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 – 2.0	0	Soil, domestic animals and wildlife.

Limit specified by Guidelines for Canadian Drinking Water Quality (Health Canada March 2025) or Alberta Government operating approval for aesthetic, health, and operational rationale.

CU = Color 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

Drinking water data summaries

Glenmore Water Treatment Plant Summary

Bearspaw Water Treatment Plant Summary

Have you checked out our open data?

Watershed Surface Water Quality Data

Watershed Monitoring Program sampling locations

City of Calgary Water Sonde data

Wastewater Treatment Plants Effluents (as reported to AEPA)