State of Clean Water and Sanitation Systems in Canada

2025

Technical Paper

Table of Contents

Notice to reader

Executive summary

Our water and wastewater systems

Our fresh water resources

State of clean water and sanitation services in Canada

State of water and wastewater infrastructure in Canada

State of water and wastewater investment in Canada

Are water and wastewater systems in Canada prepared for the future?

Conclusion

Notice to reader

Drawing from publicly available national data up to December 2024, the purpose of this working paper is to present a basic overview of the current state of clean water and sanitation in Canada. It aims to initiate a conversation on what infrastructure we have today, how it serves Canadians, and what other data or areas of research the Canadian Infrastructure Council (Council) should consider as it embarks on its work.

The infrastructure analysis in this report is grounded in national datasets compiled by Statistics Canada and other national sources. These sources offer consistent methodologies, transparency, regular updates, and comprehensive coverage—essential for meaningful national comparisons and informed decision-making across the country. However, provinces, territories, municipalities, and Indigenous organizations could maintain their own infrastructure databases, tailored to local policy needs, regulatory requirements, and operational priorities. These jurisdiction-specific datasets often provide a higher level of detail, enable real-time monitoring, and support local innovation in planning and program delivery.

The paper was prepared as a backgrounder to support the Council. It reflects input from Housing, Infrastructure, and Communities Canada, Statistics Canada, Environment and Climate Change Canada, Indigenous Services Canada, and Crown-Indigenous Relations and Northern Affairs Canada. The paper is not part of the first National Infrastructure Assessment that is under development by the Council.

Executive summary

Access to water and sanitation services are recognized by the United Nations as human rights – fundamental to everyone’s health, dignity and prosperity. An absence of clean water and sanitation services can result in preventable health risks and contamination of the natural environment. Water and wastewater systems that treat, store, and distribute clean drinking water, and collect and treat wastewater and stormwater have been central to community development and are critical to community well-being. Clean water and sanitation services are essential to accommodating the housing required to support growing communities.

Canada possesses one of the largest fresh water supplies in the world. However, less than half of this fresh water supply is renewable and can be replenished by precipitation. Further, the vast majority of Canada’s fresh water drains northward into the Arctic Ocean and Hudson Bay. As a result, water resources can be constrained in some parts of the country during warm, dry conditions, particularly in the Prairies. Despite these limitations, Canada still has significant access to renewable fresh water by global standards.

Although Canadians enjoy high levels of access to clean drinking water and sanitation, these services are often provided by underperforming infrastructure. Survey data has shown that water systems incur significant losses in the process of distributing water to households and businesses, primarily due to leakage from pipes, joints and fittings. A number of wastewater systems in Canada do not meet federal standards for wastewater effluent regulations, resulting in untreated or undertreated wastewater being released into the environment. In 2022, about over 10% of assets were in poor or very poor condition nationally and required substantial work to avoid failure in the short-term. These assets in poor or very poor condition have an estimated replacement value of $107 billion. In addition, there remain significant gaps in the quality of clean water and sanitation services between Indigenous and non-Indigenous communities in Canada.

Against this backdrop, climate change, population growth and the resulting need for increased housing supply will continue to place pressure on clean water and sanitation systems in the coming years. Communities of all sizes will need to plan for the changing and uncertain future presented by these trends to support community growth and well-being.

This discussion paper provides a summary of the state of the key elements that make up clean water and sanitation systems in Canada, including fresh water resources, physical and natural infrastructure and the services this infrastructure provides to communities. Though various types of infrastructure interact with water systems, including irrigation and electricity, elements of these systems that are not directly necessary to support housing and communities are outside the scope of this paper.

Our water and wastewater systems

Water and wastewater systems are critical for providing affordable, safe and stable clean water and sanitation services, which are essential to sustainable, inclusive and healthy communities. Access to water and sanitation are recognized by the United Nations as human rights – fundamental to everyone’s health, dignity and prosperity.

Historically, water and wastewater systems have been central to community development as individuals settled and built homes where they would have easy access to clean water. Populations could initially only settle where fresh surface water was plentiful, such as near rivers or natural springs. Throughout history, people have devised systems to better access water and to treat and dispose of wastewater.

Water and wastewater systems are made up of: fresh water sources and receiving bodies, such as rivers, lakes, springs, and groundwater; physical and natural infrastructure, such as dams and reservoirs, wetlands, water and wastewater treatment plants, pipes, pumps, sewage systems for draining stormwater, and structures used for flood mitigation; and services provided by water and wastewater infrastructure to homes and businesses.

Drinking water, also known as potable water, is water that is suitable for consumption. It can be used for drinking or preparing food, as well as a range of other activities including cleaning, toilet flushing, laundry, watering gardens and lawns, and washing cars, houses, and paved surfaces.

The flows that exit water systems can be either wastewater or stormwater. Although effort has been made to divert stormwater from wastewater systems, stormwater still enter wastewater systems and causes combined sewer overflows, especially in older systems.

Wastewater (excluding stormwater) is used water from residential and commercial sources that contain a mixture of liquid and solid materials. About 99% of wastewater is water and 1% is a mixture of organic wastes, cleaning chemicals and anything else poured or flushed down indoor drains. Wastewater contains chemicals and micro-organisms harmful to public health and the environment. Wastewater is typically collected by sewer systems and in most cases treated before being released to the environment. Though, wastewater can also be collected by truck or disposed of on-site, such as with septic systems.

Stormwater is the result of rain or melted snow. The earth absorbs some of this water, which then percolates down into underground aquifers. Some of the stormwater finds its way through ditches to streams and rivers that flow into lakes and oceans. This type of water is not treated before it is discharged into the environment, except in systems where wastewater and stormwater flow through the same pipes. Untreated stormwater picks up and carries pollutants (e.g., tar, gasoline, microplastics, etc.) into the environment from washing over impermeable surfaces (e.g., roofs, pavements, and roads).

Fresh water, drinking water and wastewater systems are interconnected. Fresh water is extracted from rivers, lakes, streams and groundwater sources, treated, and delivered to communities as drinking water for use and consumption. In combined sewer systems, used water from households and industries (e.g., wastewater) and stormwater from rain and melted snow are collected and treated before being discharged back into rivers, lakes, streams, and groundwater sources. In separated sewer systems, wastewater is collected and treated, while stormwater is collected separately and discharged without treatment in nearby watercourses and waterbodies.

Water and wastewater systems are also heavily interconnected with other built and natural infrastructure systems that support communities. For instance, hydroelectric dams need water to convert potential energy stored in a reservoir behind a dam to mechanical energy, while water plants need energy to process water that could be used for consumption.

Water and wastewater systems are critical for supporting housing and communities. In 2022, there were more than 3,300 water treatment facilities across Canada that provided drinking water that is safe for human consumption and nearly 4,000 wastewater treatment plants and lagoon systems that remove contaminants from wastewater before it is released back into the environment. Hundreds of thousands of kilometres of pipes transport water to and from these facilities. In 2021, over 33 million Canadians were served by water treatment facilities, while in 2022 over 32 million Canadians were served by wastewater treatment facilities.[1] Communities that are not connected to municipal systems tend to rely on private wells or trucks to deliver drinking water and independent systems, such as septic systems, or small-scale collective systems to provide sanitation services, while in 2022 over 32 million Canadians were served by wastewater treatment facilities.[2]

Our fresh water resources

Clean fresh water is an essential resource. We use it for manufacturing, energy production, irrigation, recreation, such as swimming, boating, and fishing, and for domestic use. It also protects plant and animal biodiversity.

Canada has one of the largest fresh water resources in the world, with 20% of the world’s total fresh water.[3] Canada has more inland waters than any other country with over two million lakes and rivers. These waters flow to the Atlantic, Pacific, and Arctic coasts, crossing international, provincial, and territorial boundaries.

The area that drains all precipitation received as runoff or base flow (groundwater sources) into a particular river or set of rivers is called a drainage basin or watershed. Smaller watersheds combine to form regional watersheds, which join others to create continental watersheds. Canada’s continental watersheds are the Atlantic Ocean, Hudson Bay, Arctic Ocean, Pacific Ocean, and Gulf of Mexico.

While 20% of the world’s total fresh water supply is in Canada, less than half of this supply - about 7% of the total global renewable fresh water supply - is considered renewable. The remaining 13% of global fresh water that is found in Canada is non-renewable water retained in lakes, underground aquifers, and glaciers and cannot be replenished by precipitation within a human timescale. However, Canada still has significant access to renewable fresh water by global standards, with over 76 million cubic metres (m³) per person compared to about 5.4 thousand m³ per person globally in 2021.[4]

Figure 1: Canada has among the largest fresh water resources per capita in the world

Note: The data for these G20 countries are from the Food and Agriculture Organization of the United Nations (FAO) (2021). AQUASTAT Database. Total renewable fresh water resources per capita (cubic metres).

Despite Canada’s significant access to renewable fresh water, these resources are distributed unevenly across the country. The majority (60%) of Canada’s fresh water drains northward into the Arctic Ocean and Hudson Bay, leaving a minority share available in the southern regions, where 90% of the population resides. As a result, water resources can be constrained in some parts of the country during warm, dry conditions, particularly in the Prairies.

Drought (a shortage of precipitation over an extended period) is a natural phenomenon in the Canadian Prairies, and multi-year droughts have been recurrent events throughout history. Droughts can cause a variety of problems for local communities, including damage to ecosystems, crops, and a shortage of drinking water. In these conditions, community-level water uses compete with irrigation, which can contribute to the depletion of water resources. Dry conditions associated with drought also increase the risk of wildfires. Over the last 120 years, at least five major droughts have occurred in the Canadian Prairies, some of which have lasted nearly a decade. As global temperatures continue to increase, droughts are expected to become more frequent.

Figure 2: Canada has abundant fresh water, but more than half flows to watersheds that are not accessible to most Canadians

Note: This figure shows the drainage areas across Canada. From “Water Sources” by Environment and Climate Change Canada (ECCC). 2013.

Fresh water governance

Fresh water management in Canada is a responsibility shared among federal, provincial, territorial, and First Nations governments. Different levels of government have different jurisdictional roles related to water management.

The Constitution Act, 1867, provides the framework for the division of powers between federal and provincial governments. Under the Act, federal jurisdiction applies to the conservation and protection of oceans and their resources, fisheries, navigation, and international relations, including responsibilities related to the management of boundary waters shared with the United States of America. The federal government also manages water in its own “federal house”, which includes federal lands (e.g., national parks), federal facilities (e.g., office buildings, labs, penitentiaries, military bases).

Aboriginal and treaty rights are recognized in Section 35(1) of the Constitution Act, 1982. Section 35 defines “Aboriginal peoples of Canada” as including First Nations, Inuit and Métis in Canada. Water-related rights recognized under Section 35 include travel and navigation, as well as rights to use water for domestic, spiritual, ceremonial, recreational, or cultural purposes.[5]

Within their boundaries, Canadian provinces and territories have the primary jurisdiction over most areas of water management and protection. Most of these governments delegate certain authorities to municipalities, such as drinking water treatment and distribution, wastewater treatment operations of urban areas, and the wetland management. Quebec, for example, has delegated the powers for wetland management to municipalities. Provinces and territories may also delegate some water resource management functions to local authorities that may be responsible for a particular area or river basin.

Most major uses of water in Canada are permitted or licensed under provincial water management authorities. Each one develops its own regulations to address specific local needs and conditions, including unique geographical, ecological, and social characteristics. Provinces and territories can tailor their regulations to address specific regional challenges, such as varying climate conditions, industrial activities, agricultural practices, and population density. Finally, shared federal, provincial and territorial responsibilities include agriculture, national water issues, and health.

The Canada Water Act, which is administered by the federal Minister of Environment and Climate Change, provides a framework for collaboration among federal, provincial, and territorial governments in matters relating to water resources. This includes collaboration on research and the planning and implementation of programs relating to the conservation, development and utilization of water resources. Currently, there are over 40 agreements under the Act. The Government of Canada is undertaking a review of the legislation.

The Government of Canada established the Canada Water Agency to improve fresh water management in Canada by providing leadership, effective collaboration federally, and improved coordination and collaboration with provinces, territories, and Indigenous Peoples to proactively address national and regional transboundary fresh water challenges and opportunities.

First Nations often have customary laws and by-laws under the Indian Act related to the preservation, management, conservation and use of water on reserve and traditional lands, rivers and waterways. They are also involved in transboundary fresh water management, including through water management boards that govern the control and movement of water resources. Fresh water is often sacred and at the centre of all life for Indigenous peoples. For many, water permeates every aspect of existence.

State of clean water and sanitation services in Canada

Clean water and sanitation services are critical for the health and safety of Canadians. They provide safe drinking water, help maintain a clean and healthy environment, and protect our communities from flooding. Contaminated water and poor sanitation are linked to transmission of diseases such as cholera, diarrhoea, dysentery, hepatitis A, typhoid, and polio. Absent, inadequate, or inappropriately managed water and sanitation services expose individuals to preventable health risks.

Water and wastewater systems are also key sources of community resilience to climate change. For example, sewer systems provide critical drainage functions during periods of heightened flood risk. Further, building water source redundancy and storage capacity into drinking water networks reduces the impacts of droughts. Aging water infrastructure itself can be a source of climate change vulnerability for towns and cities; the failure of wastewater or drinking water infrastructure systems during emergencies can have significant health consequences and/or necessitate community evacuation.

Governance of clean water services

The responsibility for ensuring a safe drinking water supply is shared between the federal, provincial, territorial, municipal governments and First Nations. The federal government, primarily through Health Canada, is responsible for establishing national standards and guidelines, such as the Guidelines for Canadian Drinking Water Quality.[6] These guidelines serve as a framework for regulatory practices implemented the provinces and territories, based on the advice of the Federal-Provincial-Territorial Committee on Drinking Water and following public consultation.

The regulation and oversight of public drinking water predominantly fall under the jurisdiction of provinces and territories, who are responsible for implementing and enforcing the standards set by the federal government, and adapting them to local conditions and needs. The provinces and territories also have the authority to manage water resources, regulate water supply systems, and ensure the safety and quality of drinking water.

Municipal governments play an important role in the treatment and distribution of drinking water within their local jurisdictions. They handle the maintenance of relevant infrastructure, such as water treatment plants and distribution pipes, and ensure compliance with provincial and territorial regulations and federal guidelines. Municipalities also have the authority to enact local by-laws and policies that address water use, conservation, and local service regulation.

On First Nation lands south of the 60th parallel, responsibility for drinking water management is currently shared by First Nations and the Government of Canada. First Nations manage and operate their water and wastewater systems, and design and build their facilities. Indigenous Services Canada (ISC) provides advice and financial support to First Nation communities for their public water and wastewater systems and ensures that drinking water quality verification monitoring programs are in place. North of the 60th parallel, territorial governments are responsible for safe drinking water in all communities, including Indigenous communities. On an exceptional basis, ISC funds housing and community infrastructure in select First Nations in the Yukon and the NWT; they have no role in Nunavut as its Indigenous population is exclusively Inuit.

In 2013, the Safe Drinking Water for First Nations Act (the 2013 Act) came into force to enable the development of federal regulations to support First Nations' access to clean, reliable drinking water and effective treatment of wastewater. However, First Nations shared several concerns with the 2013 Act, including: lack of adequate, predictable and sustainable funding; lack of recognition of Aboriginal rights; potential infringement of Aboriginal and treaty rights; lack of protection of source water; and insufficient engagement on issues that directly affect First Nations.

On December 22, 2021, the Federal Court and the Manitoba Court of Queen’s Bench (now the Manitoba Court of King's Bench) jointly approved an agreement to settle class action litigation related to safe drinking water in First Nations communities: the Safe Drinking Water for First Nations Class Action Settlement Agreement. This Settlement Agreement commits Canada to making all reasonable efforts to ensure individual class members living on First Nation lands have access to safe drinking water in their homes, whether from a public or private water system, in perpetuity, to support implementation of this commitment, Canada committed to spending at least $6 billion in existing funding by March 31, 2030, towards the construction, upgrades, operations, and maintenance of water infrastructure on First Nation lands. The Settlement Agreement also committed Canada to making all reasonable efforts to repeal the 2013 Safe Drinking Water for First Nations Act and replace it with legislation that is developed through consultation with First Nations. This act was repealed in 2022 and work on new legislation is advancing.

Drinking water usage

In 2021, total drinking water use in Canada reached 4.9 billion m³. More than half of potable water use (55%) is by households, followed by industry (28%). Despite a downward trend in drinking water use, Canada’s per capita water use is high by global standards. In 2021, average daily drinking water use nationally was 401 litres (L) per person.[7] While this has declined from 485 L per person in 2011, this is still significantly higher than most peer countries.[8]

A similar trend is exhibited when focusing on residential water consumption. Average daily residential use per capita was 223 L per person in 2021, down from 251 in 2011.[9] However, this is still significantly higher than most peer countries. For example, the average daily residential drinking water use in Europe was 124 L per person.[10] This is at least partially driven by higher prices for water in these countries. According to EurEau, average water pricing in Europe was nearly €4/m³, compared to an average water pricing in five large cities in Canada of about CAD$2.00/m³ (approx. €1.3/m³⁾.[11]

A significant and increasing portion of Canada’s drinking water use is attributed to losses from the distribution system. Water losses at the national level have increased from 13% in 2011 (673 million L) to 17% in 2021 (806 million L) of total drinking water use.[12] While the specific causes of this increase are not fully understood, it can likely be attributed to some combination of leaks from aging infrastructure, unauthorized consumption, and metering or data calculation errors.

Drinking water usage varies significantly across Canada, ranging from 283 L per person per day in Manitoba to 709 L per person per day in Newfoundland and Labrador.[13] Differences in consumption across provinces can be attributed to a number of factors, including higher water losses and differing levels of water metering and conservation practices. Figure 3 below shows average daily consumption of drinking water by province and territory per capita.

Figure 3: Total usage of drinking water varies significantly across Canada

Note: Figure shows a breakdown of the average total daily water use per person by province. From Statistics Canada. Table 38-10-0271-01 Potable water use by sector and average daily use. 2023.

Consumption levels can be heavily influenced by the mechanisms through which consumers pay for water and wastewater services. Pricing mechanisms that utilize water metering and require consumers to pay for water based on the volume of water consumed can be effective for promoting efficient water usage. This can include tiered pricing mechanisms that charge more based on the volume consumed, encouraging consumers to adopt water-saving habits.

Canadians pay for water and wastewater services through a variety of mechanisms, including:

• Flat rates: a set rate that is charged on a monthly basis regardless of the volume of water used. Flat rates do not distinguish between high and low volume users, which can result in a disproportionate share of the cost of service being borne by lower volume users.
• Uniform volumetric rates: a constant cost per unit of water or wastewater that does not vary depending on the amount used. This is a user-pay approach where metres are used to monitor usage, and those who use more, pay more, providing an incentive for conservation. Provinces with higher levels of water metering exhibit lower levels of drinking water usage.
• Block Volumetric Rates: specified and varying rates for set volumes of water usage (i.e., blocks). Block structures provide utilities with the flexibility to customize rates to achieve multiple objectives. For example, the lowest block in an increasing block rate can be set intentionally low to maintain a level of affordability for low-income users.
• Development charges: one-time fees for new development or redevelopment, where the costs are borne by the developers or final occupants rather than by the existing system users or taxpayers. These charges are focused on recovering the capital costs of expansion from serving new developments.
• Municipal taxes: while less common practice currently, funding water through property taxes was common practice in Canada in the past and is still common in Quebec and for stormwater services in many municipalities.

In addition to water metering, many municipalities and provinces in Canada have implemented water conservation programs. These programs often include public education campaigns, rebates or incentives for water-efficient appliances (like low-flow toilets and showerheads), and guidelines for water-efficient landscaping practices. Further, some provinces have specific regulations and guidelines aimed at improving water efficiency in various sectors, such as agriculture, industry, and municipal water systems. These regulations may include requirements for water reuse, leak detection, and efficient irrigation practices.[14]

Drinking water quality

Canadians enjoy high levels of access to drinking water, with the vast majority of Canadians having access to safely managed water services.[15] However, interruptions and long-term drinking water advisories to drinking water services are still experienced, particularly in Indigenous, small, and remote communities. These interruptions in access typically result in drinking water advisories.

Drinking water advisories are public health protection messages about real or potential health risks related to drinking water. These advisories are generally precautionary, meaning they are typically issued before drinking water quality problems occur. The advisories can take 3 forms: do not consume, do not use, and boil water. Boil water advisories are by far the most common, representing about 98% of the drinking water advisory data each year.

Most boil water advisories are issued because the equipment and processes used to treat, store, or distribute drinking water break down, require maintenance, or have been affected by environmental conditions. In 2021, this accounted for 90% of boil water advisories, with the remaining 10% caused by contamination from bacteria, including E. coli. Equipment and processes related to advisories are often exacerbated by operational or staffing challenges.

In 2020, almost half of off-reserve public infrastructure owners had not issued a drinking water advisory, 17% were unknown, and the remaining 35% of respondents had issued at least one advisory.[16] Some provinces or territories had issued a higher proportion of advisories than others. For instance, at least 90% of respondents in Prince Edward Island and the Yukon had not issued a drinking water advisory. On the other hand, 58% of respondents in Newfoundland and Labrador and 52% of respondents in New Brunswick had issued at least one drinking water advisory.

Between 2010 and 2021, the majority of boil water advisories were issued in communities of 500 or fewer people. Boil water advisories are more common in communities of this size because of the unique challenges they face, such as limited resources and operational capacity. For example, a broken water main in a larger city is usually isolated and repaired quickly by staff with no need for a boil water advisory. In smaller communities, the same problem may take longer to fix as they may not have the funds to make the investment required. In these cases, a boil water advisory may be issued while repairs are completed.

Figure 4: Interruptions to drinking water services occur disproportionately in smaller communities

Note: Figure shows the percentages of boil water advisories by community size. From Environment and Climate Change Canada, Canadian Network for Public Health Intelligence (2022) Drinking Water Advisories application

Governance of sanitation services

All levels of government share the responsibility for managing the collection, treatment and release of wastewater effluents. This shared responsibility necessitates close cooperation and collaboration among federal, provincial, territorial and municipal governments, as well as Indigenous governing bodies. The federal government regulates wastewater systems through the Wastewater Systems Effluent Regulations (WSER), established under the Fisheries Act and administered by Environment and Climate Change Canada.[17] These regulations set out required national effluent quality standards for wastewater discharged from wastewater treatment facilities, ensuring that harmful substances released into water bodies are minimized to protect fish, fish habitat, and human health. The national effluent standards are designed to be achievable through secondary-level wastewater treatment. The WSER apply to owners and operators (municipalities, Indigenous communities, federal, provincial or private entities, etc.), and are a key measure in reducing the impact of wastewater on Canada’s aquatic ecosystems.

Though the WSER is legally binding, the regulations do not apply to wastewater systems located in the Arctic regions (Nunavut, Northwest Territories, and north of the 54th parallel in Newfoundland and Labrador and Quebec), as further research is required to set appropriate standards for the extreme climatic conditions found in those areas. Though, provincial and territorial regulations may still apply.[18] Wastewater releases from these northern systems remain subject to the pollution prevention provisions of the Fisheries Act. Similarly, wastewater systems that collect an average daily volume of less than 100 m³ of influent per year are excepted from the regulations but remain subject to the Act.

In communities where major construction or upgrades to existing wastewater infrastructure are required to meet the effluent quality standards, a transitional authorization may be issued under the regulations to allow time to plan, finance and upgrade wastewater systems.

In addition to federal authorities, provincial governments typically issue licenses or permits to establish, construct and operate wastewater systems. There are also varying provincial and territorial wastewater regulations and practices in Canada governing the treatment and release of wastewater effluent. In cases where provincial or territorial wastewater regulations are deemed equivalent to WSER, a bilateral equivalency agreement may be established if there is interest from a province or territory to reduce the administrative burden and increase collaboration with the federal government. Once the application of the federal regulations is lifted, the WSER no longer applies, and the provincial or territorial regime becomes the sole applicable regime. There are two equivalency agreements currently in place, with Yukon (signed in 2014) and with Quebec (signed in 2018).

There are currently no distinct federal regulations that specifically govern the management of stormwater in Canada. However, some key federal legislation such as the Fisheries Act and Canadian Environmental Protection Act, 1999 (CEPA) contribute to the management of toxic substances that can be carried by stormwater. Generally, provinces and territories develop unique policies and regulations that directly impact stormwater management and set standards for stormwater discharge in their respective environment. Furthermore, municipal governments also develop specified policies and regulations regarding stormwater respective to their own needs. Additionally, municipal governments are responsible for the design, construction, operation, and maintenance of stormwater management infrastructure, including storm sewers, retention ponds, and natural and hybrid infrastructure.

Wastewater treatment

In 2022, the volume of municipal wastewater discharged into the environment in Canada was 5,661 million m³.[19] This has remained relatively stable since 2013, ranging from 5,348 million m³ to 6,162 million m³.[20] In 2022, 96% of all municipal wastewater (including combined sewer overflows) underwent some treatment to remove contaminants before being discharged back into the environment.[21]

For wastewater, national effluent quality limits have been established by the federal government through the WSER that can be achieved through secondary treatment. A number of communities are still served by wastewater systems that undertreat effluent relative to this limit. Between 2016 and 2021, the proportion of reporting municipal wastewater systems meeting quality regulatory standard effluents dropped slightly, from 81% to 76%.[22] By contrast, the effluent volume meeting the standards increased slightly from 70% to 71%.[23]

There are three authorizations that allow the release of effluent that does not meet the effluent quality standards under the WSER. Authorizations are for specific reasons and are time limited. [24] The authorizations are:

• Transitional authorizations – extensions to allow facilities to upgrade their systems.
• Temporary bypass authorizations – authorizations to exceed the standards of the regulations for maintenance and construction activities.
• Temporary authorization to deposit unionized ammonia – authorizations for systems complying with the effluent quality standards but have issues with ammonia.

In municipal wastewater systems, the water used from showers, toilets, laundry, dishwashing, and drains are pumped to wastewater treatment facilities. Municipal wastewater can be treated to various levels, each of which includes specific activities or technologies (see Figure 5 below). The treatment method for wastewater is dependent upon the types of contaminants in the sewage, the receiving environment for the treated wastewater, and effluent requirements based on local, provincial, and federal regulations.

Wastewater treatment plants utilize differing levels of treatment to remove contaminants from wastewater before its discharged into the environment, including:

• No treatment: no treatment process or only screening and/or grit removal.
• Primary treatment: removing a portion of suspended solids and organic matter by physical and/or chemical processes.
• Secondary treatment: removing organic matter and suspended solids using biological treatment processes and secondary settlement.
• Tertiary treatment: removing specific substances of concern (solids, nutrients and/or contaminants) after secondary treatment using a number of physical, chemical or biological processes.[25]

The level of treatment applied to wastewater varies significantly by provinces and territories. Saskatchewan, Alberta, and Yukon had 100% of its wastewater treated using secondary treatment or better, while Prince Edward Island, Ontario, and Manitoba were near 100%. Newfoundland and Labrador had the highest proportion of its wastewater (43%) discharged to the environment with no prior treatment.[26]

Figure 5: The quality of wastewater effluent released into the environment varies significantly across Canada

Note: This figure shows the proportion of wastewater discharged by province or territory in 2022. From Statistics Canada. Table 38-10-0124-01 Wastewater volumes discharged from municipal sewage systems by treatment category (x 1,000,000); Table 38-10-0100-01 Combined sewer overflow discharge volumes (x 1,000,000). 2024. Note: Combined sewer overflow values are not available for Quebec past 2018 and are thus not included in this graph. Data not available for Nunavut and the Northwest Territories.[27]

State of water and wastewater infrastructure in Canada

Water and wastewater infrastructure can be defined as the basic physical or natural structures needed to manage water, wastewater, and stormwater. This includes dams and reservoirs, water and wastewater treatment plants, sewer networks for collecting and transporting wastewater and stormwater, and built or natural assets that promote flood mitigation (e.g., wetlands, dykes, and permeable surfaces). It also includes networks of pipes and pumps to distribute drinking water to residents and commercial and industrial facilities. Canadians rely on these systems to deliver clean drinking water to homes and to collect and transport wastewater for treatment before being released back into the environment.

Water, wastewater and stormwater infrastructure is composed of multiple components, including:

• Water infrastructure:

• Local distribution pipes, to provide potable water directly to Canadian homes, businesses, and institutions, and transmission pipes, for moving water from its source to treatment locations and to storage.
• Water reservoirs, to store water prior to transmission and distribution of water; water pumping stations, to move water from one location to another and ensuring a steady flow of potable water to end users; and water treatment plants, to ensure that municipal potable water is drinkable.

• Wastewater infrastructure

• Sewer pipes and pump stations, to collect and transport wastewater.
• Wastewater treatment plants, lagoons, and storage tanks, to treat and store wastewater.

• Stormwater infrastructure

• Stormwater collection pipes, open ditches and culverts in diameter, to collect and transport stormwater.
• Stormwater pump stations, stormwater management ponds, and all other end-of-pipe stormwater management/treatment facilities that treat, store, or manage stormwater.
• Natural or hybrid infrastructure, such as bioswales, stormwater wetlands,
  permeable pavement, and rain gardens, that intercepts, absorbs, filters or holds stormwater, to help reduce the amount of runoff entering sewers during rain events.

Water infrastructure

Water is withdrawn from surface water or groundwater sources and treated before it gets pumped into homes and businesses. The quality of the source water, as well as the applicable drinking water quality regulations, determine the method and level of water treatment.[28] Treatment may involve several stages of filtration to remove suspended particles, debris, and algae, as well as disinfection methods such as chlorination and treatment with ultraviolet light to kill or inactivate bacteria and virus and to purify the water.

After treatment, municipal water systems distribute water to homes, institutions, businesses, and other consumers via a network of water mains and service lines buried under roads and sidewalks. These water distribution networks are typically maintained by local governments.

In 2021, the main source of water for 88% of dwellings in Canada was municipal water systems.[29] Households that are not connected to municipal water systems typically source drinking water from private wells. Small water systems across Canada’s North often utilize trucks to deliver drinking water to citizens. However, this figure does not include dwellings located in Yukon, Northwest Territories and Nunavut, households located on reserves and in other Aboriginal settlements in the provinces; and households consisting entirely of full-time members of the Canadian Armed Forces.

Wastewater and stormwater infrastructure

Wastewater and stormwater services include collecting and treating wastewater generated by residential and commercial sources, discharging wastewater safely back into the environment, preventing flooding from runoff of precipitation, and protecting water quality from contaminants that build up on surfaces in urban areas.

In some cases, wastewater and stormwater is managed through combined sewer systems, where sanitary sewage and stormwater flow through the same pipes. These systems can be problematic when there is heavy precipitation and snowmelt, causing raw sewage to be discharged into surface water and waterways. Municipalities are actively working to convert combined systems to separate systems.[30]

Under separate sewer systems, sanitary sewage collection is isolated from stormwater collection. The separation of sanitary sewage from stormwater runoff can reduce the load on stormwater infrastructure and treatment facilities and mitigate or eliminate sanitary sewage overflows.

In 2022, the proportion of the population served by municipal wastewater systems remained stable over the past decade at about 83%.[31] The proportion of the population served by each treatment category has also remained relatively stable with around 28%, 41% and 13% of the total population for tertiary, secondary, and primary treatments, respectively.[32] About 1% of the population was served by systems discharging untreated wastewater.[33] Communities without access to municipal systems typically rely on independent systems, such as septic systems, or small-scale collective systems for wastewater disposal.

A variety of factors, including Canada’s physical geography and population density influence the proportion of population served by municipal wastewater systems. For example, it can be more challenging to provide centralized wastewater services in communities where the population is spread over a large geographical area. The majority of small communities in Canada’s North rely on passive systems to treat wastewater, such as wastewater stabilization ponds, lagoons, and treatment wetlands, and for the smallest of systems, sometimes a septic field.

The proportion of the population served by municipal wastewater systems and the level of treatment of these systems varies significantly across the country. The proportion of population served by municipal wastewater systems varied in 2022 from 49% in Prince Edward Island to 88% in Quebec. Alberta had the highest proportion of population (72%) served by tertiary-level wastewater treatment, while Yukon had the highest proportion of population (68%) served by secondary-level wastewater treatment. Nova Scotia had the highest proportion of population (36%) served by primary-level wastewater treatment. A significant proportion of the Newfoundland and Labrador population (32%) was served by municipal systems that discharge wastewater to the environment with no prior treatment. The majority of systems that discharge untreated wastewater are located in coastal communities.

Figure 6: The proportion of population served by municipal wastewater systems and the level of treatment employed varies significantly across the country[34]

Note: This figure shows the proportion of the population served by municipal wastewater systems by treatment level for provinces and territories in 2022. Data not available for Nunavut and Northwest Territories. From Statistics Canada. Table 38-10-0125-01 Population served by municipal wastewater systems by treatment category. 2024; Statistics Canada. Table 17-10-0009-01 Population estimates, quarterly. 2025.[35]

Infrastructure condition

Data from Canada’s Core Public Infrastructure Survey (CCPI) provides a picture of the current condition of Canada’s water and wastewater infrastructure. The survey asks public infrastructure owners to provide information on the quantity and physical condition of all existing infrastructure assets. These ratings range from very poor (major work or replacement required urgently) to very good (sound physical condition).

The majority of existing water and wastewater infrastructure is in good or very good condition at the national level. However, over 10% of existing assets for most asset types were reported to be in poor or very poor condition nationally and require substantial work to avoid failure in the short-term. There are significant discrepancies regionally with existing infrastructure in some parts of the country in considerably worse condition than others. Further, there is a significant infrastructure gap between Indigenous and non-Indigenous communities in Canada.

For existing local water pipes, about 14% were in poor or very poor condition in 2022 while about 61% were in good or very good condition. Ontario had the highest proportion of existing local water pipes assessed as very good at nearly half of all its pipes (45%). On the other hand, over a quarter of existing pipes in Newfoundland and Labrador are rated as very poor or poor (23%).

For existing water treatment plants, 8% were in poor or very poor condition in 2022 while 68% were in good or very good condition. All jurisdictions have a higher proportion of very good or good ratings relative to very poor or poor ratings. No jurisdiction exceeds a 14% proportion of ratings being very poor or poor while good or very good ratings are as high as 94% (Nunavut). Over half of all existing facilities in every province and territory rates their existing water treatment plants as very good or good.

Figure 7: While the majority of water, wastewater, and stormwater existing infrastructure is in good or very good condition, action is needed in the near-term to improve infrastructure in poor or very poor condition

Note: This figure displays the distribution of existing water, wastewater, and stormwater assets by condition rating. Statistics Canada. Table 34-10-0288-01 Inventory distribution of core public infrastructure assets by physical condition rating. 2025.

Like other asset classes, water, wastewater and stormwater assets can be grouped into linear assets, such as pipes, and non-linear assets, such as water treatment facilities. Condition assessments on existing linear wastewater assets focus on existing sewer pipes with a diameter of less than 450 millimetres (mm) as this type of asset forms the majority of inventory counts for existing wastewater assets as a whole. In 2022, 13% of existing sewer pipes were assessed as very poor or poor, while 57% were rated as good or very good. The condition of the remaining 10% was unknown. Provinces such as Saskatchewan, Prince Edward Island (PEI), Nova Scotia, and Manitoba have a higher proportion (over 15%) of existing small sewer pipes that are very poor or poor. On the other hand, Quebec, New Brunswick and Alberta have more than 60% of their existing small sewer pipes rated as good or very good.[36]

For existing wastewater treatment plants, very good or good assessments make up the largest share of condition ratings for most provinces in 2022, Quebec, Nova Scotia, and Alberta all have very good or good rating proportions that exceed 70%, compared with the national average of 61%. Meanwhile, Manitoba has the highest proportion of very poor or poor assessments which sits at 28%. It is important to note that these asset condition ratings are unrelated to the level of treatment provided by the plant (see Figure 7 above for the proportion of population served by municipal wastewater systems and the level of treatment employed by province).

In 2022, 10% of existing small stormwater pipes (diameter of less than 450 mm) were assessed as very poor or poor, and 53% as good or very good. 19% of these pipes had an unknown assessment. For medium stormwater pipes (diameter between 450 and 1500 mm), 8% of existing stormwater pipes were assessed as very poor or poor, compared with 54% as rated as good or very good. 20% of existing medium sewer pipes had an unknown assessment. For large stormwater pipes (diameter greater than 1500 mm), 6% were assessed as poor or very poor, while 54% were good or very good. Assets with an unknown condition made up 29% of large pipes.

Five jurisdictions had at least 50% of their existing small stormwater pipes, seven jurisdictions reported at least 50% of their existing medium stormwater pipes rated as good or very good, and eight jurisdictions had a majority of large stormwater pipes in good or very good condition. Yukon had the largest share of assets in poor or very poor condition for small and medium stormwater pipes (49%). For large stormwater pipes, no jurisdiction had more than 15% of assets in poor or very poor condition.

For existing stormwater management ponds and wetlands, 7% of assets were rated poor or very poor, while 55% of assets were rated very good or good in 2022. Very poor or poor assessments made up a small proportion of each province and territory’s distribution, with Ontario and Nova Scotia having the highest proportion in these categories at 11%. For other existing stormwater management facilities, 5% of assets were rated poor or very poor, while 53% of assets were rated very good or good. Very poor or poor assessments made up a small proportion for most province and territory’s distribution. Saskatchewan had the highest proportion in these categories at 26%, followed by Nova Scotia at 19%.

Infrastructure asset value and ownership [37]

Replacement value data for existing assets from CCPI provides useful information on the cost to replace assets owned by public organizations (excluding First Nations governments) based on current prices and costs. Based on this data, the replacement value of all drinking water, wastewater, and stormwater assets was $963 billion in 2022. Assets in poor or very poor condition, which are at risk of failure in the near-term, had an estimated replacement value of $107 billion. An additional $109 billion of assets had an unknown condition rating, which includes $85 billion of pipes that are likely to be found underground, not including force mains and culverts.

For drinking water assets, the replacement value of all assets was $357 billion in 2022, with assets in poor or very poor condition making up $41 billion of the total. Pipes that transport and deliver drinking water made up the majority of this replacement value at $275 billion. Water treatment facilities represented $48 billion in replacement value, followed by other non-linear water facilities (e.g., storage facilities) that made up the remaining $34 billion. Water pipes also made up the majority of assets in poor or very poor condition, with a replacement value of $34 billion, followed by treatment facilities and other non-linear facilities at $4 billion each.

For wastewater assets, the replacement value of all assets was $359 billion in 2022, with assets in poor or very poor condition making up $45 billion of the total. Sewer pipes that transport sewage from homes made up the majority of this replacement value at $238 billion. Wastewater treatment facilities represented $84 billion in replacement value, followed by other non-linear wastewater facilities (e.g., storage facilities) that made up the remaining $23 billion. Sewer pipes also made up the majority of assets in poor or very poor condition, with a replacement value of $27 billion, followed by treatment facilities at $14 billion and other non-linear facilities at $3 billion each.

For stormwater assets, the replacement value of all assets was $247 billion in 2022, with assets in poor or very poor condition making up $20 billion of the total. Stormwater pipes that collect and transport stormwater made up the majority of this replacement value at $177 billion, followed by culverts and open ditches at $38 billion and $18 billion, respectively. Stormwater management facilities and drainage pump stations represented the remaining $28 billion in replacement value. Stormwater pipes also made up the majority of assets in poor or very poor condition, with a replacement value of $11 billion, followed by culverts at $5 billion.

Figure 8: Pipes responsible for delivering drinking water, and collecting wastewater and stormwater make up the vast majority of assets by replacement value

Note: This figure displays the distribution of existing water, wastewater, and stormwater replacement values by asset and condition rating. Statistics Canada. Table 34-10-0284-01 Estimated replacement value of core public infrastructure assets, by physical condition rating (x 1,000,000). 2025.

Based on replacement values of existing assets, local and regional government are responsible for most drinking water, wastewater, and stormwater assets that are owned by public organizations. In 2022, municipalities owned 74% of drinking water assets, 77% of wastewater assets, and 78% of stormwater assets. Other local and regional governments were responsible for 25%, 22%, and 8% of drinking water, wastewater, and stormwater assets, respectively. Federal, provincial, and territorial governments were responsible for less than 1% of drinking water and wastewater assets. In contrast, provincial and territorial governments owned 14% of stormwater assets.

Assets owned by municipalities are primarily within urban municipalities. Of all assets owned by municipal governments, urban municipalities owned 80%, 83%, and 85% of all drinking water, wastewater, and stormwater assets, respectively.

Figure 9: Local and regional governments are responsible for most drinking water, wastewater, and stormwater assets

Note: This chart shows the breakdown of publicly owned assets by levels of government. This data does not include First Nations governments. Statistics Canada. Table 34-10-0284-01 Estimated replacement value of core public infrastructure assets, by physical condition rating (x 1,000,000). 2025.

State of water and wastewater investment in Canada

Water and wastewater infrastructure is capital-intensive due to the technical complexity of treatment infrastructure and the high construction costs of unearthing and repairing vast networks of linear assets. As a result, maintaining infrastructure in a good state of repair while meeting increasing demand for services requires significant and sustained investment.

Over the past 40 years, investment in drinking water infrastructure has been volatile – with various peaks and troughs. On average, Canada has spent 0.2% of Gross Domestic Product (GDP) on water infrastructure, including contributions from the private sector, all levels of government and Indigenous communities. This is relatively low by global standards. Internationally, advanced economies invest on average between 0.4 and 0.6% of their GDP in water infrastructure. Following the “Great Recession” of 2008, investments in drinking water increased significantly, peaking at 0.4% of GDP in 2010 ($7.2 billion in constant 2012 dollars).[38] Investments made largely in the aftermath of the Great Recession has led to a 99% increase in the net stock, the total capital stock after factoring depreciation, of drinking water infrastructure between 2000 and 2015 at the national level. However, capital stock peaked in 2015 and has since declined by 5%. This implies that investment has not been sufficient to cover the depreciation of existing assets.

The extent to which this recent decline in net stock presents risks to future service provision is unclear, however, there are signs that drinking water assets are under increased stress. For example, water losses in the distribution system have increased significantly over this time, which is likely in part due to deteriorating assets. Further, total water usage could increase moving forward due to high population growth.

On average, Canada has spent 0.2% of GDP annually on wastewater infrastructure over the past 40 years. Since 2000, annual investment in wastewater infrastructure has increased by 82%, reaching its highest level in 2023 at $5 billion (constant $2012). As a result of this sustained investment, the net stock of wastewater infrastructure has increased steadily over time. Since 2000, the net stock of wastewater infrastructure has increased by 30% at the national level.

In spite of this increase in net stock, both the quantity and the level of treatment of wastewater discharged into the environment have been stable since 2013 (data pre-dating 2013 is not available). Further, the number of municipal wastewater systems in compliance with effluent quality limits prescribed by the WSER has declined from 81% in 2016 to 76% in 2021, although the total volume of wastewater in compliance has increased (from 66% to 71%).

The public sector is the primary investor in water and wastewater infrastructure in Canada. In 2023, the public sector contributed 98% of all investment ($5.0 billion) in drinking water infrastructure and 96% of all investment ($6.2 billion) in wastewater infrastructure.[39] Investment in both drinking water and wastewater infrastructure has increased significantly in recent years with municipalities responsible for over 90% of all investment.[40]

Figure 10: The public sector is the primary investor in water and wastewater infrastructure in Canada

Note: This chart shows a total investment in waterworks (drinking water) and sewage (wastewater) infrastructure since 2019, split between the public and private sector. Statistics Canada. Table 36-10-0608-01 Infrastructure Economic Accounts, investment and net stock by asset, industry, and asset function (x 1,000,000). 2025.

The remaining useful life ratio (RULR) is an estimate of the average number of years a stock of assets remaining before needing to be repaired or replaced, divided by its average expected service life, creating a ratio that indicates the percentage of the asset class that remains. It reflects the aging of assets and investment in repairing, replacing and adding assets, such as a new water treatment plant. This is more useful for comparing trends within jurisdictions than ratios between them. For example, the variation in remaining useful life ratio is greatest in the territories and smaller provinces, indicating that differences may be due to individual projects having greater impact on the average, rather a structural problem in these jurisdictions.

Although the average remaining useful life ratio for wastewater infrastructure is estimated to be above 40% for waterworks assets and for wastewater assets in all provinces, decreasing ratios in some regions suggests that investments are not keeping up with aging stock. Nationally, the RULR has been trending down since 2019 for waterworks assets and slowly trending up for wastewater assets. The RULR is declining for both asset classes in Newfoundland and Labrador and Manitoba, indicating that the stock of these assets may be depreciating faster than they are being replaced or renewed.

Figure 11: The average remaining useful life of waterworks and wastewater infrastructure differs by province and territory but remains above 50% for waterworks and above 40% for wastewater

Note: These graphs show recent trends in the remaining useful life of waterworks (drinking water) and sewage (wastewater) infrastructure by province and territory. Statistics Canada. Table 36-10-0611-01 Infrastructure Economic Accounts, average age and remaining useful service life ratio by asset and asset function. 2025. Data presented in this report are sourced exclusively from Statistics Canada and harmonized national datasets to ensure methodological consistency and national comparability. Although provinces, territories, municipalities, Indigenous organizations could maintain their own infrastructure databases tailored to local needs, only national datasets are used here to support reliable national analysis.

Water and wastewater infrastructure projects are often financed by multiple levels of government. For example, the Canada Infrastructure Bank (CIB) recently loaned up to $140 million to support five communities with water and wastewater infrastructure projects in Manitoba, with additional funding from the Province of Manitoba and Infrastructure Canada through the Investing in Canada Infrastructure Program.[41] This infrastructure will be publicly owned and operated by the municipalities, who are responsible for the delivery of these essential projects.

Municipalities use a variety of sources to fund infrastructure projects, including utility rates, general revenue (e.g., property tax), and debt financing for large capital projects, with loans obtained through financial institutions at negotiated interest rates, bond issuance, or through loans and grants from other levels of government or provincial bodies. Municipalities differ in how self-sufficient water and wastewater services are, ranging from fully funded through utility rates and others funded through general revenue without metering. While some projects have successfully used a private-public partnership model to deliver wastewater projects, most water project investment is public at the project-level.

From 2011 to 2021, the total operating and maintenance cost for drinking water plants that primarily treat surface water (e.g., water from sources open to the atmosphere such as rivers, lakes and reservoirs) increased by 35%, or $267 million. Over the same period, the cost per volume of water increased by $73 per thousand m³ (49%), indicating that this increase was not driven by increased demand. Of the increase in cost per volume, labour ($30) accounted for the greatest share, followed by materials ($18), energy ($14), and other operations and maintenance ($12).[42]

For water treatment plants that primarily treat groundwater and groundwater under the direct influence of surface water, total operating and maintenance costs increased by 27%, or $48 million, from 2011 to 2021. Over the same period, the cost per volume increased by 52%, indicating that this increase was not driven by increased demand. Of the increase in cost per unit, labour ($95) accounted for the greatest share, followed by materials ($30), energy ($41) and other operations and maintenance ($8).[43] The cost per volume of these facilities is more than double that of treatment plants that primarily treat surface water, primarily due to lower production volumes per treatment plant.

Operating and maintenance cost data are not available for wastewater treatment facilities at this time.

Are water and wastewater systems in Canada prepared for the future?

Canada’s future infrastructure needs will be heavily linked with major trends that are changing the shape of communities across Canada, namely population growth and the resulting need for increased housing supply, and climate change. Communities of all types will need to plan for the changing and uncertain future presented by these trends to support community growth and well-being.

Population growth and housing

Population growth is expected to place increasing pressure on infrastructure systems, including water and wastewater infrastructure. Canada’s population has been growing at a rapid pace in recent years, fuelled by increased immigration. In 2021, Canada’s population reached almost 37 million, up 5.2% from 2016. This increase in population requires additional housing. As a prerequisite for adequate housing, basic infrastructure for safe drinking water and sanitation must be in place.

The population in Canada is not only growing in magnitude but is also increasingly urban. While the total population increased by 5.2% between 2016 and 2021, census metropolitan regions experienced growth of 6.1 %.[44] As shown in Table 6.1, population density is increasing by greater magnitudes closer to downtown in most major cities. In 2021, urban fringes and near, intermediate, and distant suburbs have developed in most urban centers (see also Figure 12).

Figure 12: Population growth is increasing density in urban and suburban areas of Canada’s major cities

Note: These graphs show the percentage of population growth within major Canadian cities by proximity from downtown. From Statistics Canada. Census of Population, 2016 and 2021 (3901).

As a result of urbanized population growth, higher-density housing is representing an increasing share of new residential properties. While many Canadians prefer to live in low-density housing, such as single-detached houses, this type of new housing is increasingly limited in city centres because of an increasing scarcity of land. According to Statistics Canada, single-detached houses represented a smaller proportion of residential properties built from 2016 to 2021 compared with their share of the stock built before 2016.[45] Consequently, the share of denser property types, such as row and semi-detached houses, was increasing.

Population and housing growth patterns have significant implications for the development of water and wastewater infrastructure. New low-density housing developments require more pumps and pipes to connect dwellings to drinking water and sanitation services. Densifying urban cores can lead to existing water and wastewater networks being at overcapacity, requiring extensive upgrades. Despite this, providing drinking water and sanitation services to higher density housing communities has been estimated to be less expensive than lower-density communities.[46]

Climate change

Climate change is changing patterns of rainfall, snow, ice, and permafrost melt, creating water availability and quality issues, and changing the frequency and severity of water-related extreme weather and disaster events, such as floods and droughts. These changes pose substantial challenges to different types of Canadian infrastructure, including water and wastewater infrastructure.

Water and wastewater infrastructure can be affected, or overwhelmed, by climate change hazards in many ways. For example, the quality of water entering a water treatment system can be affected by a flood (e.g., contaminants from rural or urban areas) or by a wildfire (e.g., organic carbon and nitrogen runoff); these events could also directly affect the physical infrastructure itself. Shifting climate patterns, extreme weather events, and slow onset impacts have the potential to accelerate the deterioration of water and wastewater infrastructure, shortening the effective lifespan of these critical assets and affecting the services they deliver to communities and businesses.

Stormwater systems will also play a critical role in mitigating the impacts of increased precipitation, rapid snowmelt, and extreme weather events due to climate change. More frequent and intense downpours can overwhelm the design capacity of municipal stormwater management systems. Overwhelmed stormwater management systems can lead to backups that cause localized flooding or lead to greater runoff of contaminants such as trash, nutrients, sediment or bacteria into local waterways.

Many cities still use combined sewer overflow designs that integrate stormwater and sanitary sewage systems. As the severity and frequency of heavy precipitation events and freeze-thaw cycles increase, these systems will be at increased risk of being overwhelmed, increasing the risk of untreated sewage backing up into basements and/or being discharged into adjacent streams and lakes. This can cause contamination of municipal drinking water systems and can also lead to contamination of water bodies. Rising sea levels associated with climate change have also been observed to alter groundwater flows in coastal cities, increasing the likelihood of sewer overflow events as rising groundwater enters aging sewer infrastructure or builds up in areas of high permeability.

As much of Canada’s infrastructure was designed based on historical climate conditions, asset managers must now determine how to manage climate-related risks and allocate scarce dollars to adapt existing infrastructure. Investing in adaptation measures in the short-term can preserve levels of service and avoid future costs, while avoiding faster deterioration and loss of service. For example, the Financial Accountability Office of Ontario estimates that a proactive strategy to adapt wastewater infrastructure at the earliest opportunity would lead to 35% lower costs up to the year 2100 in a medium emissions scenario when compared to a reactive strategy where assets are adapted at the scheduled time of renewal.

Conclusion

Clean water and sanitation services provided by water and wastewater infrastructure are essential for the health and well-being of communities in Canada. While Canadians have widespread access to clean drinking water and sanitation, these services are often provided by underperforming infrastructure. In addition, there are often significant gaps in the quality of clean water and sanitation services between Indigenous and non-Indigenous communities in Canada. Moving forward, population growth and housing demand, combined with the increasing effects of climate change, will require water and wastewater systems that are able to serve more households while being increasingly resilient to changing weather patterns.

Understanding the current state of clean drinking water and sanitation systems is a critical step towards Canada’s first National Infrastructure Assessment (NIA). This discussion paper represents a snapshot of key topics and publicly available, Canada-wide data. Over the next 25 years, decision-makers will need to consider what are the most significant threats to providing affordable, reliable community mobility services to Canadians.