Sodium in Sudbury and districts drinking water supplies

March 28, 2022

To: All local health care providers

Sodium levels are routinely monitored in all government regulated water supplies in Ontario. The aesthetic objective for sodium in drinking water is 200 mg/L, at which point it can be detected by a salty taste. Sodium is not considered a toxic element; therefore, a maximum acceptable concentration for sodium in drinking water has not been specified.

The average intake of sodium from water comprises only a small fraction of that consumed in a normal diet. In general, healthy adults require only 1500 mg of sodium per day.2 Most Ontarians consume more than double that amount–approximately 3400 mg.2 By comparison, the highest measured sodium content in drinking water within the last several years was 155 mg/L (Table 1). Assuming a water intake of up to 2 L per day, this amounts to less than 10% of the average Ontarian’s sodium consumption.

Examples of sodium content found in common foods1

Nonetheless, sodium reduction represents an important preventive health measure. Persons suffering from hypertension or congestive heart failure may require a sodium-restricted diet, in which case the intake of sodium from drinking water may become significant. The local Medical Officer of Health is notified when the sodium concentration of drinking water exceeds 20 mg/L so that this information may be shared with local clinicians for their consideration when treating patients on sodium- restricted diets.

Table 1: Water systems reported to have sodium concentrations higher than 20 mg/L

FacilitySodium (mg/L)Resample
Blezard Valley/Capreol/Drinking Water System, 202026.1, 21.6, 37.5, 21.8, 96.926.1, 20.4, 30.1, 22.4, 88.0
C.A. MacMillan Place Well Supply, Webbwood, 201520.920.4
Chapleau Drinking Water System, 201826.323.1
Dowling Drinking Water System, 202033.8, 40.4-
Espanola Drinking Water System, 20222221.5
Falconbridge Drinking Water System, 202022.8, 22.8, 25.6-
Humarcin Residents' Organization, Sudbury, 202297.246.8
Onaping/Levack Drinking Water System, 2020109, 96.6-
Peace Valley Trailer Park, Wahnapitae, 2011 107.1-
Residence de Pionniers de Noëlville, 202097.0-
Sudbury Drinking Water System-David Street, 202054.1-
Sudbury Drinking Water System-Garson, 202155.4 68.5
Terry Wong Trailer Park, Chapleau, 2020154-
Vermilion Water Treatment Plant, 201820.420
Villa Notre Dame Well Supply, 2020 30.330.5
Warren Well Supply, 202210878.7

Sampling frequency: The Ministry of the Environment, Conservation and Parks requires that samples be taken every five years. The Medical Officer of Health is advised of water systems that contain sodium concentrations higher than 20 mg/L. Resamples are taken if the original sample is over 20 mg/L to confirm results.

Many of the distribution systems within a community may reflect a blended supply of water. Details regarding specific water supplies can be obtained by contacting the local municipal office.

We encourage clinicians to review sodium reduction strategies with all patients both for preventive care and as part of chronic disease management. More information on sodium reduction is available from the Dietitians of Canada.

  1. Health Canada. (2013, March 18). Nutrient Value of Some Common Foods. Retrieved November 21, 2017, from nutrition/healthy-eating/nutrient-data/nutrient-value-some-common-foods-2008.html
  2. Dietitians of Canada. (2017, April 6). Cut out the Salt. Retrieved March 24, 2022, from

This item was last modified on May 6, 2022