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Flouride in the Drinking Water

Tooth decay is the single most common disease in children. Municipalities add controlled levels of fluoride to our drinking water supply to help in the prevention of tooth decay. Learn about fluoridation here.

Do you have questions about the safety of fluoride added to your drinking water? Many national and international organizations support the controlled addition of fluoride to help in the prevention of tooth decay.

What is water fluoridation and why is it so important?

Water fluoridation is the process of adjusting the natural level of fluoride in our water municipal water supply to a level that will optimize dental benefits. Fluoride additives must meet standard of quality before being added to water at the recommended levels.

Water fluoridation is important because:

  • Research has shown that fluoride in drinking water reduces the number of cavities in children
  • Tooth decay is the most common chronic disease in children (five times more common that asthma and seven times more common than hay fever!)

Water fluoridation in Halton

Public water systems

  • Halton Region's Certified Water Treatment Operators add and monitor fluoride in our water supply
  • Fluoridation does not occur in the older section of Milton, although the groundwater based system contains natural fluoride of 0.1 parts per million (ppm) to 0.15 ppm.
  • When adding fluoride to the water supply, the Ontario Ministry of the Environment recommends levels of 0.5-0.8 ppm for optimal tooth decay prevention.
  • Fluoride occurs naturally in water sources and levels vary across Ontario and Halton.
  • Natural fluoride levels in Halton region are too low for the prevention of tooth decay.

Private well water

  • Halton Region does not treat or add anything to private well water.
  • Well water fluoride levels can vary substantially.
  • Well owners must maintain and test their well water for bacteria. A private laboratory will test your water to assess fluoride levels as well. Find out how to have your well water tested.

What is the evidence that water fluoridation reduces dental decay?

A number of reviews on the effectiveness of water fluoridation have been conducted over the last 10 years. Over 90 dental and public health organizations support fluoridation, including:

  • The World Health Organization
  • Health Canada
  • The Canadian and American Dental Associations
  • The Canadian Public Health Association
  • The U.S. Centers for Disease Control and Prevention (CDC)

Reviews on water fluoridation:

Are there any health risks associated with water fluoridation?

Health risks

  • At optimum levels of 0.5 – 0.8 ppm, there are no known health risks.
  • At higher levels ( > 4ppm), and long-term consumption, fluoride can cause skeletal fluorosis, osteoporosis, or bone fractures.
  • Researches continue to investigate osteosarcoma and effects on the reproductive system, kidneys, brain and endocrine system.


  • In mild cases, fluorosis appears as white flecks on the tooth surface.
  • In severe cases, brown staining and/or pitting on the tooth surface occur.
  • Fluorosis occurs when people swallow too much fluoride during early tooth formation years (ages 0-6 years for front teeth)
  • Cases are often mild and only pose a cosmetic concern.

Fluoridation and babies

  • Fluoride in the Halton water supply does not pose a health risk to your baby when preparing infant formula, however Halton Region Health Department recommends breastfeeding as the safest and healthiest way to feed your baby.
  • You should test your well water before using it to prepare formula, to ensure safe levels of fluoride.
  • Call Halton Region for more information on safe preparation and storage of formula.