Guiding the way to safer water reuse

Providing Albertans with safe and abundant water is challenging. Climate change, population growth, aging infrastructure and urbanization create a multitude of pressures on municipal water systems. Reusing urban stormwater and rainwater is an area of growing interest to address these challenges, but water reuse comes with a host of public health considerations, such as the potential impact of residual microbes on human health. Recent work by Norman Neumann, a professor in the school of public health at the University of Alberta is helping to manage the risks associated with reusing urban stormwater and rainwater, informing Alberta’s new Public Health Guidelines for Water Reuse and Stormwater Use and contributing to healthier, more sustainable communities.

Understanding the potential hazards of reusing water is important to determining how it needs to be treated to be safe. Systems designed to capture and redistribute stormwater and rainwater need to ensure the risks of the public getting sick are low. Neumann’s work looked specifically at the microbial risks of reusing stormwater and rainwater and explored innovative ways to assess and reduce these risks to the public.

“The concern with microbes,” said Neumann, “is their ability to amplify and replicate their effects. All we need is for one person to get sick and then they infect others, who then infect others, and so on.” However, determining the acceptable level of microbes in reused water is not always easy. What the water will be used for, where it came from and the amount of expected human exposure are all important risk considerations. Neumann and colleagues used a quantitative risk assessment approach to examine a variety of water reuse scenarios and to identify microbial targets appropriate for the water end use.

The diverse water reuse scenarios Neumann examined identified some innovative risk reduction strategies. For example, stormwater used for irrigating recreational fields have less stringent microbial targets than stormwater used for toilet and urinal flushing. This is because when combined with management strategies like watering at night, the likelihood of human exposure to water reused for recreational irrigation is much lower than the likelihood of being exposed to reused water in your home.

Neumann’s work has the potential for significant impact. Previously, Alberta had no clear guidelines or standards in place to ensure water reuse was being done safely.

“When we started looking at this, there were standards being developed in other parts of the world,” said Neumann. “But how do you decide which regulation you follow? Many jurisdictions have conflicting guidelines and definitions of what safe water even is, and often have very different water sources and demands than we have in Alberta.”

Neumann believes that with clear guidelines, comes the potential for greater innovation. It provides developers and municipalities with a framework that supports building better infrastructure and more sustainable communities, giving them the confidence they need to invest in new and innovative water reuse systems.

“When it comes to building sustainable, safe water systems, we need to consider our future needs,” said Neumann. “The solutions and programs we implement today will impact our communities 20 years from now. The Water Innovation Program transpires multiple points of innovation—not just technology innovation, but policy and regulation innovation as well.”

Learn more about the programs offered through our Environmental Innovation strategic initiative. 

This article is part of Making Waves, an annual Alberta Innovates publication highlighting water solutions we support. You can read more stories from this issue below.