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In 2015, the United Nations (UN) released 17 Sustainable Development Goals (SDGs), which “address the global challenges we face, including those related to poverty, inequality, climate, environmental degradation, prosperity, and peace and justice.” Goal 6, “Ensure availability and sustainable management of water and sanitation for all,” has been identified as the most suitable SDG target to be at the center of an integrated approach to achieving all goals by 2030.

So, water is the foundation of all other development goals. Yet ensuring access to safe and reliable drinking water continues to be a cause for concern, even in Canada. In one of the most fresh-water rich countries in the world, many remote communities remain under boil water advisories, some of which have been in place for over 20 years. Even urban areas are facing emerging risk, as aging infrastructure threatens the reliability and quality of our water supply. The reliability of this resource continues to be a challenge and acts as roadblock to addressing other greater issues, such as maintaining sustainable cities and eliminating hunger.


Aging infrastructure

Ensuring safe and reliable water to supply to our big cities is an increasing concern as urbanization continues to intensify. As watermains age, they experience corrosion, which results in increased pipe roughness, reduced hydraulic capacity and greater leakage. Over time, this infrastructure not only becomes less reliable, but also less efficient. It is ultimately the quality of the water and its delivery which become severely compromised.

Addressing these challenges, even in developed countries, is becoming increasingly difficult as communities are faced with aging infrastructure that is unable to meet the needs of our ever-growing population. The ability to replace all deteriorating assets is unfeasible due to limitations with physical and financial resources.

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Watermain break in downtown Toronto, 2018

Consider this; watermains generally have a lifespan between 75 and 100 years. If municipal utilities target an annual replacement rate of 0.5 per cent, it would take 200 years to replace an entire distribution network, which is twice the expected service life of its components. To replace these assets within their expected service life, the annual replacement rate would need to be at least doubled and the following minimum annual commitments would be required across Canada:



60 km


47 km


26 km


24 km


16 km


15 km

For many municipalities, these targets represent a significant increase from current replacement rates and may be extremely difficult (if not impossible) to achieve due to financial and resource restrictions.

For example, approximately 11 per cent of watermains in the City of Toronto are now more than a century old, far exceeding their expected service life. If the City of Toronto was to focus solely on the replacement of this 660 km of watermain, at a rate of one per cent annually, it would take 11 years for them all to be replaced.

These challenges have motivated municipalities to shift their focus to maintenance activities, which can extend the life of this infrastructure at a reduced cost, when compared to replacement. In doing so, replacement efforts can be focused on pipes that are in critical condition or are critical components of the water distribution system.


In praise of maintenance

In many cases, municipalities can significantly extend the service life of these assets through maintenance and renewal activities. The use of technologies such as spray-in-place-pipe (SIPP) lining or cured-in-place-pipe (CIPP) structural lining can help owners extract the maximum value from their assets. There are many advantages to these methods, namely the reduced cost incurred, the minimized disruption to communities and increased volume of work that can be delivered annually. Additionally, condition assessment of the pipelines can be used to ensure timely intervention. By timing both the method of interventions and the most effective locations ensures the maximum reward for the expenditure is realized.

Most of all, asset renewal reduces the required replacements that must occur each year and allows existing assets to remain in use for longer periods of time, providing financial, social and environmental benefits. However, the primary disadvantage of these methods is that they do not produce a new pipe; one that utilizes standard fixtures and fittings. As such, many renewed assets will have unique properties, behavior and require specific maintenance procedures, which differ from both their replaced and un-renewed counterparts.

Infrastructure renewal can be used both reactively and proactively, depending on the level of risk that municipalities are willing to accept. Proactive intervention can be used to ensure high working efficiency and significantly reduce the number of annual watermain breaks. While this approach is appealing, it is also costly and would involve renewing watermains well in advance of their expected service life. This would significantly reduce the environmental, economic, and social benefits of pipeline renewal techniques.

Alternatively, a reactive approach can be used, by which timing of intervention is based on failure events within the network, such as bursts or leaks. This method can present financial benefits but would require communities to accept that aged infrastructure will remain in place until it nears the end of its service life. This approach could lead to more frequent disruptions to service, which may be unacceptable to residents or local government.


An integrated approach

Most often, creating a strategic balance between infrastructure replacement and maintenance is the most financially and operationally beneficial approach. By replacing watermain infrastructure at a sustainable pace, while simultaneously using innovative technology and targeted intervention to maximize the value stored in our existing assets, we can ensure there is clean, safe water for everyone in our urban ecosystems.

Safeguarding our water infrastructure will maintain a strong foundation for other sustainability work in our neighbourhoods, communities and broader environment. Maintenance work on watermain assets may seem like a niche technical process, but in effect, protecting that small pipe is an essential and foundational prerequisite to our quality of life.

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