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, Conservation and Parks (MECP).

Toronto’s tap water is safe to drink right out of the tap. It is clean, inexpensive and environmentally friendly. Filling up a standard reusable water bottle costs less than one penny, while bottled water can cost as much as 200 times more.

The City of Toronto meets or exceeds the regulations set by MECP for drinking water, which are some of the most stringent regulations in the world.  While bottled water can come from all over the world and may not follow stringent regulations, Toronto’s tap water is drawn from local sources to ensure the water supply is reliable, safe and sustainable.

In addition, using Toronto’s tap water is environmentally better than bottled water since it does not require the production and disposal of plastic bottles as part of supplying the water.

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 the 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 MECP regarding the operations, capital and operating budgets of the drinking water system.

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 surface between one and five kilometres away from shore.
  • Lake water passes through screens to remove large debris. Water is disinfected by using either chlorine or ozone.
  • Alum or poly-aluminum chloride is added to the water to bring particles in the water together and form larger particles called floc.
  • The water travels through settling basins to allow larger particles to settle to the bottom. The clear water at the top proceeds to filters containing gravel, sand and carbon to remove suspended impurities and microorganisms.
  • Before water is pumped for distribution to homes and businesses, the following is added:
    • chlorine to destroy bacteria and viruses
    • fluoride to help prevent tooth decay
    • ammonia to ensure chlorine levels remain present 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.

Cloudy water

  • Water that looks cloudy is usually safe to drink and use. This cloudiness is usually temporary. The cloudy appearance is usually from air bubbles in the water that should disappear within a few minutes. Air bubbles in the water can occur for the following reasons:
    • when different temperatures of water enter the plumbing system
    • when the water has been turned off during construction
    • with valve changes in the distribution system (a valve is a device that regulates, directs and controls the flow of safe drinking water in watermains)
  • 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. If the water is still cloudy or sediment appears, please contact 311 to initiate a water quality service request.


  • Chlorine is used in the drinking water process to control bacteria, algae and viruses.
  • The range of chlorine used is set by the MECP (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 or add ice and a slice of lemon, lime or fruit to the water.


  • Fluoride is added to Toronto’s drinking water to reduce the risk of tooth decay.
  • Fluoride levels in Toronto’s drinking water are regulated in Ontario under the Safe Drinking Water Act administered by the Ministry of the Environment, Conservation and Parks.
  • Learn more about fluoride from Toronto Public Health.

Discoloured tap water

  • Discoloured or rusty tap water can be caused by a number of different factors.
  • If only one tap is affected, this indicates a private plumbing issue. You may wish to contact a plumber.
  • If all taps are affected, this may be a result of plumbing work on your property, construction on a watermain in the area, or nearby fire hydrant use. Get tips on how to resolve the issue.

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