What is sodium?

Sodium is a naturally occurring mineral in food and water and is a necessary element of human health. Typically, the consumption of sodium from food is much higher than from drinking water.

How does sodium get into the drinking water?

Sodium in raw water sources can vary dramatically depending on the source – lakes, rivers or wells. The naturally occurring sodium levels in the groundwater aquifers that the Municipality draws from for drinking water have historically ranged between 28 mg/L and 66 mg/L. No sodium is added as part of the Municipal water treatment process.

How much sodium is acceptable in drinking water?

The Guidelines for Canadian Drinking Water Quality and Ontario Drinking Water Quality Standards (ODWS) set an aesthetic objective (i.e., non-health related) for sodium in drinking water at 200 mg/L, at which point it can be detected by a salty taste by the average person. The province has not specified a health related maximum acceptable concentration in drinking water in the ODWS.

Under the Safe Drinking Water Act, the Ontario Drinking Water Systems Regulation (170/03) requires that a report be made to the local Medical Officer(s) of Health if a sodium result exceeds 20 mg/L in a sample of drinking water. When a sodium sample result in drinking water exceeds 20 mg/L, the Medical Officer of Health informs physicians and other health professionals to help people following sodium restricted diets determine their sodium intake.

How often is sodium testing conducted on the Mississippi Mills Drinking Water Supply?

Under the Ontario Drinking Systems Regulation (O. Reg. 170/03), drinking water systems are required to test water supplies for sodium once every five years. All samples are sent to an external accredited laboratory for analysis. Mississippi Mills carries out this mandatory testing and includes the data within the drinking water reports published and posted online annually.

How much sodium is in drinking water supplied to Almonte?

In 2023, the sodium level in the Almonte water supply was tested and results ranged from 28 mg/L to 55 mg/L. Sodium levels above 20 mg/L are not uncommon in drinking-water; in fact, several municipalities in Ontario have sodium levels that regularly exceed 50 mg/L. Previous notices for sodium levels are included on this webpage for reference. 

How will sodium levels greater than 20 mg/L affect my health?

The human body requires sodium to maintain blood pressure, control fluid levels and for normal nerve and muscle function. Health Canada puts the adequate intake of sodium for healthy people (14-50 years old) at 1,500 mg per day; however, individuals on sodium restricted diets should consider the amount of sodium in the water when calculating their sodium intake. When sodium levels in drinking water are at 20 mg/L, drinking two litres per day would contribute 40 mg of sodium to a person’s diet. For healthy adults, this level of sodium in drinking water does not pose a health risk.

Sodium Analysis in the Almonte Ward Municipal Drinking Water System - September 2023 Public Notice

Sodium Levels in Almonte Water System - 2018 Public Notice 

Sodium Levels in Almonte Water System - 2013 Public Notice