Fact Sheet: About watermain breaks and how residents can prepare their pipes for winter


About watermains and why they break 

  • Watermains break more frequently in winter months – November to March because low temperatures can cause soil to freeze and expand, creating frost loading or force applied to a watermain.
  • Most watermains are made of cast or ductile iron, and are about 1.8 metres deep, just below the frost line.
  • External corrosion can cause pits to develop in cast or ductile iron pipes, weakening them over time.
  • Smaller cast iron watermains constructed in the 1950s/60s are more prone to break as they have thinner walls.  
  • Leaks can also erode the ground or ‘bedding’ surrounding a watermain, ultimately causing the pipe to collapse.
  • North York, Scarborough and Etobicoke experience the highest break rates as their watermains are located in predominantly acidic clay soil as opposed to sand.


Working to reduce watermain breaks

  • The City replaces approximately 35 to 50 km of watermains each year, and rehabilitates more than 130 km to help extend the life of its watermains.
  • Watermain replacements are determined based on several factors, including age, break frequency, material, operational requests, hydraulic performance, future growth, and minimizing cost and disruption to the community by co-ordinating with other construction programs (such as road, sewer, gas and hydro).
  • Rehabilitation is done using one of the following methods:
    • cathodic protection, which involves installing a sacrificial anode (magnesium cylinder) to an existing watermain so that it corrodes instead of the watermain. 
    • structural lining, which involves inserting fibreglass within an existing watermain to form a new pipe wall. This technology is best suited to situations where larger diameter watermains need to be renewed and the cost of open-cut (trenching) and traffic disruptions are a significant consideration.


Responding to watermain breaks

  • Residents should call 311 to report a watermain break.
  • Toronto Water staff are available 24 hours a day, 7 days a week to respond to calls.
  • The City also has a number of contractors already in place who can help with a spike in watermain repairs, if needed.
  • Once a watermain break has been reported, depending on the severity, repairing the watermain can take up to 24 hours and sometimes longer.
  • The first steps are to determine the location and the severity of the break and, if required, turn off the flow of water.
  • The next step is to acquire underground locations of utilities (such as Enbridge and Toronto Hydro) to ensure excavation can take place safely.
  • While the repair is underway, residents and businesses may be without water and will be advised of water service disruption and the repair schedule.
  • Repairs can be made using a clamp or by replacing the deteriorated section of pipe.
  • Temporary road repairs can take an additional one to two days (permanent road repairs become part of the City's longer-term capital coordination projects).



  • Approximate cost to repair average watermain break       $13,000
  • 2015 budget to improve the watermain system                 $146 million (approx.)


Basic statistics

  • Kilometres of  watermains                                                     6,074
  • Average age of watermains                                       59 years old
  • 80-to 100-year-old watermains                                             12.95%
  • Watermains more than 100 years                                         10.77%
  • Average number of breaks/year                                            1,600
  • Total breaks in 2013                                                               1,403
  • Total breaks in 2014                                                              1,632                              
  • Total breaks in 2015 (to November 16)                                1,536
  • Approx. length of watermains replaced/year                      35 to 50 km
  • Approx. length of structural lining/year                                30 to 50 km
  • Approx. length of cathodic protection /year                         100 to 130 km


You can learn more about watermain breaks at

How residents can prepare their pipes for cold weather:

  • Ensure you know where the main water shut-off valve is in your home and how it operates (in case your pipes burst).
  • Wrap foam pipe insulation around pipes most prone to freezing (e.g. near outside walls, crawl spaces and attics). 
  • Seal air leaks in your home and garage, especially in areas where pipes are located.
  • Unscrew any hoses, turn off the outdoor water supply and let the taps drain.
  • If your pipes are prone to freezing, you may wish to contact a plumber for advice on how best to protect your home.
  • Keep areas that contain indoor pipes above 8°C, especially near the water meter.
  • If you are away, have someone check your property regularly.
  • In extreme cold weather, for your own peace of mind, you can choose to run a pencil-thin stream of water to ensure some movement of water in the pipes. However, you will be charged for the water used if you choose this step.

More tips to prevent frozen pipes are available at

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