There's Only One Water — and Its Quality and Quantity Are Inseparable

The water quality-quantity nexus is another illustration of how water is intimately linked with multiple aspects of life on earth.

It seems water is a lot more important and integral to life than we routinely think.

Some years ago, scientists began talking about the water-energy nexus — the idea that it takes water to produce energy and energy to produce water. For example, electric power plants require vast amounts of water for cooling, and meanwhile water and wastewater treatment plants are major consumers of energy.

Next to gain attention was the water-food-energy nexus — the idea that farming is the largest consumer of the world’s freshwater and that more than one-fourth of the energy used globally is spent on food production and supply.

The latest iteration of this concept is the water quality-quantity nexus. Much has been said and written about global water scarcity — how hundreds of millions of people live in areas where water supplies are severely limited.


Current thinking holds that, often, water quality and water quantity are intimately connected. For example, a river flowing past a community could be an abundant source of water for all domestic purposes, but it’s not if that water is severely polluted and the community lacks the money and facilities to clean it.

Or, in the case of groundwater, sometimes after too much pumping from an aquifer, the levels of natural compounds grow dangerously high as the amount of water diminishes. Other times, as in coastal areas, excessive pumping drops the water table to below sea level and then saltwater intrudes, making the water unfit for drinking and even for irrigation.

These issues are by no means limited to developing countries. In fact, the water quality-quantity nexus is very much on the radar of the National Association of Clean Water Agencies. The organization projects that water issues in the arid West and the Southeast will become more acute with climate change and the growing demand for water.

One example of the problem is the Rio Grande on the Texas-Mexico border. The concentrations of agricultural and industrial pollutants increase markedly during the low-flow summer season. Pathogen levels can increase nearly one-hundredfold during that time of year. 


The connection between quality and quantity suggests new approaches to expanding and improving water supplies. For example, according to the Columbia Water Center at Columbia University, approaches that use conservation to extend supplies could be more cost-effective than traditional methods that aim to improve the quality of diminishing supplies.

For example, conservation initiatives that reduce demand on aquifers could enable groundwater levels to rise, helping to prevent saltwater intrusion and lowering concentrations of harmful natural contaminants.

NACWA, according to a policy statement on its website, is working on these issues through its national policy agenda and collaboration with local, state, regional and national organizations. For example, NACWA is addressing the emerging challenge of salinity.

“Across the country, there is a growing national trend in freshwater salinization from road salt application, water reuse, desalination, water softeners and high natural background levels,” the statement says. The association is working with U.S. EPA staff to discuss how that trend is affecting municipal water agencies.

In addition, NACWA has developed a concept paper along with the Western Coalition of Arid States. Roundtable discussions with various stakeholders in the Southwest revealed that many water-quality and -quantity challenges extend well beyond those states’ borders “and thus demand a greater national focus.”


The water quality-quantity nexus is another reminder of how interconnected water is with every phase of human life and our societies and how by looking deeper we can devise more effective and more diverse solutions to water problems.

This concept is summed up well in a paper co-authored by Thushara Gunda, a scientist at Sandia National Laboratories. The paper, Water security in practice: The quantity-quality-society nexus, states, “As precipitation patterns shift, and as water is ever more intensively exploited, managing water resources in an integrated manner will be increasingly imperative to ensure water security in the future. … Successful management of water resources needs to account for water quantity and water quality aspects of the physical resource as well as associated societal dimensions of both.”

You can learn more about NACWA’s work around this issue at source-issues.  


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