Information about Guelph’s tap water and fluoride

Guelph is a groundwater community—our water is drawn from wells tapped into underground water sources. Our excellent groundwater supply requires minimal treatment and additives in order to meet provincial and national safe drinking water quality standards.

The City of Guelph does not add fluoride to its tap water. And it never has. Water from Guelph’s groundwater sources does contain low levels of naturally occurring fluoride that may be distributed across the city. Levels of naturally occurring fluoride are well below standards set out in Ontario’s Safe Drinking Water Act, 2002 (SWDA). See the map below for information about the latest test results (2014) for naturally occurring fluoride in Guelph water.

The City of Guelph samples the drinking water supply for fluoride every five years as per the requirements of the SDWA (Regulation 170/03). Samples taken in 2009 and 2014 showed an average level of naturally occurring fluoride of 0.29 mg/L, with a maximum level of 0.77mg/L. This is well below the Ontario Drinking Water Quality Standards’ safe drinking water limit of 1.5mg/L for naturally occurring fluoride. Details about naturally occurring levels of fluoride can be found in the City’s annual water quality reports.

The last local referendum on the topic of fluoridating Guelph’s tap water was held in 1972; seventy-seven percent voted against it. Choosing to add fluoride to our tap water would increase the cost of supplying water to customers and would result in a water rate increase. At this time, the City of Guelph has no plans to add fluoride to the drinking water supply.

Many municipalities across Ontario and Canada add fluoride to tap water. Professional health organizations state that fluoride at the recommended level is a safe and effective means of reducing tooth decay and does not pose a risk for health concerns.

If you have questions about oral hygiene, or health-related questions about fluoride, please contact Wellington-Dufferin-Guelph Public Health at 1-800-265-7293.

For more information on the Guelph’s tap water, including water quality and testing, visit