Building a Climate-Resilient City: Water supply and sanitation systems

Submitted by Christian Ledwell | published 20th Apr 2017 | last updated 13th May 2019
water-supply

Introduction

Climate change impacts involve threats and costs touching on all aspects of contemporary municipal life, and many of its effects on urban environments have yet to be effectively quantified. These growing climate risks have clear implications for local economies and the financial well-being of municipal governments. Well-planned adaptation measures can improve the quality of urban life as well as protect lives and infrastructure, strengthen community ties and improve economic performance.

The Building a Climate-Resilient City series was prepared for the City of Edmonton and the City of Calgary by the International Institute for Sustainable Development in collaboration with the University of Winnipeg’s Prairie Climate Centre. This series makes recommendations for steps that cities can take as part of their municipal adaptation planning to build their resilience to climate change. It explores three key principles of resilience building: robustness (strong design), redundancy (building extra capacity into systems to act as fail-safe networks) and resourcefulness (citizen empowerment).

This policy brief* examines ways to build resilience in the water supply and sanitation system as a contribution to building urban resilience. Its purpose is to highlight areas of best practice for developing a more resilient water supply and sanitation system.

*The text below provides the key messages and recommendations from the brief and summarises some of the economic and financial factors that can support the building of climate-resilient cities. See the full text for much more detail.

Lessons Learnt

  • Redundancy in water supply should be a policy priority with the flexibility to shift between surface and groundwater options.
  • Highly decentralized water supply and sanitation options are now feasible; they provide resilience and complement centralized systems.
  • Water conservation and green infrastructure options for stormwater management are proven approaches for reducing climate risks.
  • Building and maintaining a water supply system resilient to climate shocks requires “multi-barrier” methods that strengthen all infrastructure components.

Envisioning a Resilient Water Supply and Sanitation System

Critical infrastructure such as water supply and sanitation systems, is essential for the functioning of both daily and vital services to communities, and as such, it is also essential that water supply and sanitation infrastructure is resilient to climate change. Building more robust networks, integrating redundancies and encouraging resourcefulness into these sectors can assist in reducing the risk of failure arising from climate impacts. 

  • Building Robustness: A climate-robust water supply and sanitation system draws upon multi-barrier water protection principles—essentially an integrated system of procedures, processes and tools that prevent or reduce the contamination of drinking water from source to tap. Investing in the ecological integrity of water supply sources and their watersheds is an increasingly important component of the multi- barrier approach. Through the 20th century, water supply and sanitation—like energy systems—have become ever more centralized and reliant on key water and wastewater treatment plants. A basic resilience strategy means hardening these infrastructure nodes to climate impacts.  

  • Promoting Redundancy: The principle of redundancy for water supply and sanitation is best understood as the capability of subsystems to source water and treat wastewater in the event that key nodes in the network are disrupted. Water supply system redundancy includes source water supply diversity. Redundancy in the sanitation sector is strongly related to the adoption of modular, decentralized wastewater treatment technologies, an extremely active cleantech sector globally and in Canada. The range of new wastewater technologies is truly impressive, including drop-in small footprint and energy-efficient secondary treatment replacement reactors for conventional wastewater plants. Highly decentralized wastewater treatment to the individual household is also possible and should be examined.

  • Encouraging Resourcefulness: Resourcefulness is the intelligent use of
    existing resources by empowered citizens and government. In the water and sanitation sector, it typically involves the creative re-use and retention of water to minimize the utilization of conventional infrastructure, and some degree of autonomy from the water and sewerage networks in the event of system malfunction. A basic example is rooftop rainwater harvesting using cisterns for potable water supply, an ancient technology still practiced widely.

How Canada is and could be building robustness, promoting redundancy and encouraging resourcefulness in water supply and sanitation systems is discussed in much more detail in the brief. To read more about applying the above principles to water supply and sanitation systems in an urban resilience-building context, please refer to the full text.

Recommendations

Strategic

  • Perhaps the foremost strategic decision cities face is the degree to which they choose an ecosystem-based approach to protecting water sources, and develop the required relationships with upstream and downstream watershed management agencies and municipal governments. Green infrastructure for source water protection, water quality treatment and climate adaptation generally will not be widely adopted unless managers and the public are broadly aware of ecosystem service concepts and applications. Well-designed ecosystem service approaches create a rural-urban relationship that can foster mutually beneficial green infrastructure investments.
  • Conduct climate analyses on source watersheds. Such an exercise will help managers understand the range of future hydro-climatic risk and advocate more clearly for infrastructure investment including green infrastructure options.
  • Conduct risk management scenario planning exercises for managers that consider the joint effects of simultaneous flooding and power outages and drought and power outages as a second phase of the source watershed climate impact analysis.
  • Conduct a scoping study on decentralized water supply and wastewater treatment with respect to emerging technologies, economic development opportunities for cleantech leadership and the benefit of increased climate resilience. Consider the 2013 flood as a benchmark scenario and examine how decentralized treatment systems could have reduced vulnerabilities.
  • Develop position papers regarding water use efficiency and decentralized water treatment as forms of cleantech innovation and as distinctive attributes of the investment value proposition worthy of demonstration at residential, industrial and subdivision scales.

Regulatory/Administrative 

  • Conduct a review of the infrastructural and institutional mechanisms that would permit reallocation of existing water supply in crisis situations (such as from industrial to residential), including a review of the regulatory vulnerabilities associated with First In Time First In Right (FITFIR) water allocation system in the context of drought.
  • Review the regulatory context for decentralized water supply and wastewater treatment facilities (cisterns, grey water recycling, and decentralized water and wastewater treatment). Identify regulatory obstacles to innovative applications of decentralized water technologies and develop a municipal strategy for creating water technology innovation testbeds.

Economic Instruments

  • Review tariff structures for residential and industrial water supply and consider alternative tariff structures for consistency with social justice, equity and conservation objectives.
  • Analyze water-use efficiency among industrial and residential consumers; review the international state-of-the art standard for industrial water efficiency and consider incentives for water conservation and for encouraging redundant supply—such as the ability to switch to groundwater.
  • Conduct a feasibility analysis of water trading systems for industrial consumers in order to drive down demand. Include a review of international precedents for water supply trading.
  • Review the North American experience with stormwater levies (Mississauga) and stormwater retention credits (Washington, D.C.), as well as rebates based on xeriscaping, to establish potential largescale green infrastructure systems for urban stormwater management. 

Voluntary/Community Linkages

  • Develop public education materials for a “water smart” culture, with household-level conservation and low-impact development such as permeable surface materials for paved areas, rainwater collection systems and bioswales.
  • Promote citizen science in the educational system for water and hydrology, including crowd-sourced monitoring of precipitation, temperature, streamflow and water quality to augment official data gathering to introduce water stewardship and climate change concepts to school-age children.