The City of Toronto ensures that residents, businesses and visitors have access to clean, safe drinking water. This is done through a complex water treatment process and continuous testing so that water always meets or exceeds the Safe Drinking Water Act set by the Ministry of the Environment and Climate Change (MOECC).

Toronto’s tap water is continuously tested, monitored and analyzed to ensure it meets the strict standards of Toronto Public Health, the Province of Ontario and Government of Canada.

Toronto Water’s accredited lab:

  • tests drinking water every six hours (over 6,000 times a year)
  • conducts more than 20,000 tests at the water treatment plants annually
  • conducts 15,000 bacteriological tests on samples collected from the water distribution system annually

See the most recent drinking water quality and system reports submitted to the Ministry of the Environment and Climate Change.

Each day, the City of Toronto treats more than 1 billion litres of safe drinking water at four water treatment plants, which operate 24 hours a day, seven days a week.

How treatment works

  • Water is collected from Lake Ontario through intake pipes deep below the lake and one to five kilometres away from shore.
  • Lake water passes through screens to remove large debris and then through filters to remove additional impurities. Water is disinfected by using either chlorine or ozone.
  • Alum or Poly Aluminum Chloride is added to the water to form a jelly-like substance that joins larger particles called floc, and goes through additional filtration.
  • The water travels though settling basins so larger particles settle to the bottom. The clear water at the top proceeds to filters containing gravel, sand and carbon to remove suspended impurities and bacteria.
  • Before water is pumped for distribution to homes and businesses, the following is added:
    • chlorine to destroy bacteria, algae and viruses
    • fluoride to help prevent tooth decay
    • ammonia to ensure chlorine levels remain consistent as water travels through the distribution system
    • phosphoric acid, which is used for corrosion control to help create a barrier between residential lead pipes and drinking water

Supply, storage and distribution

To ensure an uninterrupted water supply, there is a computerized process control system overseen by Toronto Water staff. The aim is to distribute superior quality water in a reliable, cost-effective and environmentally sound manner. Staff monitor:

To ensure adequate water pressure and supply, Toronto is split into six pressure zones and subdivided into 13 pressure districts, which are continuously monitored and adjusted based on demand. Additional water is stored in tanks and reservoirs, which helps maintain pressure and enough supply during peak periods and emergencies such as fires, watermain breaks and power outages.

Drinking water system & financial reports

See the most recent reports submitted to the Ministry of the Environment and Climate Change regarding the operations, capital and operating budgets of the drinking water system.

Cloudy water

  • Water that looks temporarily cloudy is safe to drink and use.
  • The cloudy appearance is from air bubbles trapped in the water and should disappear within a few minutes. Bubbles can get trapped:
    • when different temperatures of water enter the plumbing system
    • when the water has been turned off during construction
  • To reduce the cloudy appearance:
    • run a cold water tap to allow the air to escape
    • pour some cold water into a glass.The air bubbles will rise to the surface and clear up within a few minutes

Chlorine

  • Chlorine is used in the drinking water process to control bacteria, algae and viruses.
  • The range of chlorine used is set by the Provincial Safe Drinking Water Act and is continuously monitored by the City to ensure the water is safe to drink.
  • If you are sensitive to chlorine taste and odours, fill a pitcher with water and let it stand overnight in the refrigerator.

Fluoride

  • Fluoride is added to Toronto’s drinking water to reduce the risk of tooth decay.
  • The level of flouride used is set by the Provincial Safe Drinking Water Act and is carefully controlled and monitored by the City.
  • Learn more about fluoride from Toronto Public Health.

Earthy or musty smell/taste

  • Earthy, musty smell and/or taste can occur in late summer or early fall and can be the result of naturally-occurring algae and high water temperatures in Lake Ontario.
  • The water remains safe to drink during these events.
  • Taste and odour can also be a result of a private plumbing issue. Learn more about potential causes and what to do.

Lead and drinking water