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

Below you will find information about hardness ratings for Calgary and what they mean for your dishwashers, washing machines and water softeners.

Questions about your drinking water?
For answers to common drinking water questions like water hardness, water taste, odour or appereance, or water pressure, visit Drinking Water in Calgary.

Water hardness reports

Learn more about water hardness, including the difference between hard and soft water, how water hardness affects dishwashers and washing machines, and the water hardness ratings for different parts of Calgary.


What is water hardness?

Water hardness is caused by calcium and magnesium in the ground and surface water. If either of these minerals are present in your drinking water in high concentrations, the water is considered hard. These minerals come from rock such as limestone that dissolves in our river system. The result of hard water is difficulty making lather or suds for washing and a build-up of minerals on taps and other fixtures.

Water containing low concentrations of calcium or magnesium is called soft water. Municipalities with soft drinking water often have higher incidences of water pipe corrosion (low pH). The degree of hardness in drinking water is commonly classified in terms of its concentration of calcium carbonate:

Hardness rating Concentration of Calcium Carbonate (mg/L) Concentration of Calcium Carbonate (grains/ imperial gallon)
Soft 0 to <60 0 to <4.2
Medium hard 60 to <120 4.2 to <8.4
Hard 120 to <180 8.4 to <12.6
Very hard 180 and greater 12.6 and greater

Source: Health Canada - Guidelines for Canadian Drinking Water Quality


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. Also, water softeners should be connected so that the water you are drinking is not softened.


Can water hardness affect dishwashers and washing machines?

Hard water can reduce the effectiveness of detergent. Hard water may also cause automatic dishwashers or washing machines to leave film on dishes or leave residue on clothing, and can also cause mineral build-up on mechanical parts.

The easiest solution to hard water problems is to increase the amount of detergent used in proportion to the degree of water hardness. Check with your appliance user manual or the manufacturer for instructions.


How do water softeners work?

Water softeners replace the non-toxic hard minerals with sodium or potassium. The amounts added are relatively insignificant compared to what you ingest from your food. They should not pose health problems, unless you are on a salt-reduced diet.

Most water softeners regenerate with salt and water. Regeneration is a process where the softening materials (called resins) inside the softener can be used over and over again. Once regeneration is completed, the salt and water solution is flushed into the sewer and into the environment. A correctly operating water softener will use salt and water efficiently, saving you money while reducing the impact on the environment.


How do I regenerate my water softener?

Water softeners must regenerate frequently using salt and water. How often a water softener must regenerate depends on the hardness of your drinking water supply. Water softener manufacturers often classify hardness of the water supply using the unit grains per Imperial gallon.


How hard is Calgary's water?

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

  • The lowest hardness levels are typically during spring snowmelt and the highest hardness levels are between December and February.
  • The Bow and Elbow Rivers each have different hardness levels and provide water to different parts of the city.

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.

Residents in both halves of Calgary may receive a mix of water from both treatment plants, depending on flow conditions and city water demand.


What is the hardness rating in north Calgary?

The table shows the monthly values for water hardness as expressed as Calcium carbonate CaCO3 in both milligrams per litre (mg/L) and grains per imperial gallon.

Bearspaw Treatment Plant Effluent Water Hardness (mg CaCO3) for 2021

Month mg/L CaCO 3 grains/gallon
January 188 13.1
February 194 13.6
March 181 12.6
April 179 12.5
May 170 11.9
June 137 9.6
July 133 9.3
August 146 10.2
September 151 10.5
October 159 11.1
November 169 11.8
December 178 12.4
Average 165 11.6


What is the hardness rating in south Calgary?

The table shows the monthly values for water hardness as expressed as Calcium carbonate CaCO3 in both milligrams per litre (mg/L) and grains per imperial gallon.

Glenmore Treatment Plant Effluent Water Hardness (mg CaCO3) for 2021

Month​ mg/L CaCO 3 grains/gallon
January 252 17.6
February 258 18.1
March 252 17.6
April 229 16.0
May 201 14.0
June 183 12.8
July 183 12.8
August 190 13.3
September 199 13.9
October 208 14.5
November 219 15.3
December 228 16.0
Average 217 15.2