Watermains are underground pipes that deliver a steady supply of fresh, clean drinking water to residents and businesses.

Fast Facts

  • There are more than 6,100 km of watermains in the City’s water distribution system.
  • Most watermains are metallic (made of cast iron or ductile iron). Some watermains are also made of polyvinyl chloride (PVC), concrete encased steel and other types of materials.
  • The average age of Toronto’s watermains is 61 years:
    • 9 per cent are 80-100 years of age
    • 15 per cent are more than 100 years old
  • Watermain pipes are buried about 1.8 m deep, just below the frost line.
  • The City experiences an average of 1,100 watermain breaks annually since 2016.
  • Watermains break more frequently in winter months – November to March – because low temperatures can cause soil to freeze and expand, creating frost loading or resulting in force applied to a watermain.
  • External corrosion can cause pits to develop in cast or ductile iron pipes, weakening them over time.
  • Leaks can also erode the ground or ‘bedding’ surrounding a watermain, ultimately causing the pipe to collapse.
  • Smaller cast iron watermains constructed in the 1950s/60s are more prone to break as they have thinner walls.
  • North York, Scarborough and Etobicoke experience the highest break rates as their watermains are located in predominantly acidic clay soil as opposed to sandy soil. These areas also have a higher percentage of smaller cast iron pipes constructed in the 1950s/60s.

The City is improving the watermain distribution system through the following programs:

Watermain Replacement

The City replaces approximately 30 to 40 km of watermains each year.

A combination of factors are considered when prioritizing replacement, including pipe age and material, break frequency, operational performance, future growth, and coordination with other construction projects (i.e. roads, transit, sewer, gas, hydro, etc.) in order to minimize cost and disruption to the community.

Watermain replacement is part of the City’s planned capital works. Watermain replacement generally involves excavation of the road and digging of a trench to install new watermains and replace City-owned substandard water service lines. The trench would then be resurfaced and areas affected by construction would be restored once the watermain is replaced.

Watermain Rehabilitation

The City rehabilitates more than 100 km of watermains each year to help extend the life of its watermains. This is mainly done through the following methods:

Cathodic Protection

  • Involves attaching anodes (magnesium or zinc cylinder) to an existing watermain, which then corrode instead of the watermain itself.

Structural Lining

  • An access hole is excavated to reach the existing watermain. The watermain is cleaned to ensure a smooth surface.
  • A liner is inserted in the existing watermain to help form a new pipe wall. Liners can be composed of different materials, including fiberglass and polymers.
  • The liner is then inflated and cured with hot water or steam within the existing watermain. This almost creates a pipe within a pipe and helps extend the life of the watermain.
  • Approach is best suited when the cost of open-cut (trenching) and traffic disruptions are significant.

Residents should call 311 to report a watermain break. Toronto Water staff are available 24 hours a day, seven days a week to respond to calls. Depending on the circumstances and severity of the break, repairs can take up to 24 hours and sometimes longer. Whenever possible, Toronto Water and its contractors will provide those impacted by a watermain break notice of disruptions to water supply or access.

Steps to Repair

  1. Staff will determine the location and severity of the break, and, if required, turn off the flow of water.
  2. Staff will acquire underground location of utilities (i.e. sewers, gas, electrical, etc.) to ensure excavation can take place safely.
  3. A clamp will be used to fix the hole or staff will replace the deteriorated section of pipe.
  4. Temporary road repairs will take an additional one to two days.
  5. Permanent road repairs within the public right-of-way (e.g. replacement of asphalt and concrete impacted by construction) will be undertaken. Note, this is not the same as road resurfacing.

The City flushes watermains to help renew the pipes and improve the quality of water moving through them.