Measuring What Matters: Household Water Use in the Great Lakes Region

“Measure what matters” and “You can’t manage what you can’t measure”: those may be old clichés, but they’re still goodies! Business managers everywhere know that tracking important metrics and trends and understanding the drivers behind them is essential to strategic decision-making and course-correcting when necessary.

But in the world of water management, good measurements can sometimes be hard to come by. As one of life’s precious necessities, fresh water – its quantity, quality, uses, and more – surely matters enough to measure and study with at least as much care as widget manufacturers approach their factories.

In the Great Lakes region, across the U.S. and Canada, 40 million people meet their drinking water and household water needs with the Great Lakes basin’s ground and surface water – a resource also shared with commercial and industrial users. For 50 years, in the Great Lakes region (as in other parts of the U.S.), this municipal water use has been declining, but the drivers of this trend have not been well understood.

Enter Drew Gronewold, Associate Professor at the University of Michigan’s School for Environment and Sustainability, and his team of graduate students, James Polidori and Hannah Paulson, now with the Great Lakes Commission and Wisconsin Coastal Management Program, respectively. They set to work digging into complex municipal water use data from five Great Lakes cities – teasing out residential, commercial, and industrial uses – and marrying that with data on the cities’ populations and socioeconomics to identify the drivers of water use patterns.

In a new paper published in the Journal of Great Lakes Research, Gronewold and team described their key findings, and  what they mean for water managers, policymakers, and citizens in the region.

First, they found that residential (household) water use was largely responsible for the observed reductions in usage between the study years of 1997 to 2018. (Commercial and industrial water withdrawals moved up and down as facilities entered, expanded, or left municipal areas, but the researchers excluded these variations to be able to see the impact of household usage alone.) At the same time, most of the studied cities’ populations were relatively stable or growing, so per-person residential water used was found to have decreased significantly as well.

Interestingly, those cities with the largest populations tended to have the lowest per-person water use, suggesting possible “economies of scale” in household water usage. The study authors hypothesized that these cities may benefit from multi-unit housing that requires less lawn and garden watering, or that population growth may have led to new buildings with new, high-efficiency water fixtures.

Second, the team explored the role of socioeconomic factors – including household income, inequality, race, and poverty – that might explain changes in residential water use. These variables had different relevance across different cities. Across two of the study cities, per-person water use varied statistically with the proportion of white and non-white residents, and in one city, water use decreased significantly with an increase in the population’s income inequality. Further research is needed to better understand how socioeconomic factors may impact residential water usage moving forward.

Finally, the team identified that residential water conservation measures – both behavioral and technological, with efficient appliances and fixtures – may be another large driver of reduced household water usage.

Further research will explore these questions in more depth. Gronewold, in addition to being a part of the Center for Sustainable Systems, which has a long history of water resources research, leads the new Global Center for Climate Change Impacts on Transboundary Waters. With these Centers, he will continue to collaborate with water managers, end users, communities, and interdisciplinary research partners to learn and share about the Great Lakes’ hydrology, water management, environmental impacts, and climate change adaptation. “The Great Lakes can be viewed as both a unique regional water resources system requiring customized expertise and research, and as a system that can serve as a resource for understanding and managing climate change impacts on transboundary waters across the globe,” he says.

Gronewold and colleagues conclude their research article calling for a “vision for water use policies guided not just by trends in metered water use, but also by historical and projected changes in the demographics of water users at the household and community level.” Thanks to this team’s analysis, we have “measured what matters” a little better than before, providing a deeper understanding of what has driven municipal water use changes across the Great Lakes region over the last several decades. Water managers and researchers can now turn to that vision, understanding how these dynamics may change in the future and using that to inform water policy and management.

Gronewold and colleagues are interested to hear from readers at public or private water utilities who collect, or want to start collecting, water use data and may want to collaborate. The lack of detailed data available to researchers has hampered essential research like this study, which can be of value to the utilities themselves, as well as many other facets of society. If you are interested in discussing a collaboration, please reach out to css.info@umich.edu.

Author: Shoshannah Lenski, Associate Director of the Center for Sustainable Systems, University of Michigan School for Environment and Sustainability