Stricter water and wastewater treatment standards, deeper aquifer production, long-haul pipelines, and desalination each contribute to more energy consumed in the pursuit of water. Protecting drinking water quality from the output of water treatment plants for the sake of public health and discharge water quality from wastewater treatment plants for the sake of ecosystems requires nontrivial amounts of energy. As standards for water and wastewater treatment tighten, energy consumption for water treatment increases. While efficiency of new treatment technologies and methods increases over time, standards usually tighten in parallel.
Simultaneously, water entering water and wastewater treatment plants becomes more polluted with time. As the population grows, discharges into waterways increase while the purity of that water decreases. For example, concerns grow about pharmaceuticals (including birth control hormones and narcotics) in sewage streams, which require new equipment and ongoing investments of energy and capital to remove from wastewater.1David Sedlak, Water 4.0: The Past, Present and Future of the World’s Most Vital Resource (New Haven: Yale University Press, 2014). Increased biofuels production from corn ethanol in the United States causes additional runoff of nitrogen-based fertilizers and other pollutants, requiring more energy to clean the water downstream.2K. M. Twomey, A. S. Stillwell, and M. E. Webber, “The unintended energy impacts of increased nitrate contamination from biofuels production,” Journal of Environmental Monitoring 12 (2010), 218-224. If pollution infiltrates the groundwater, as has happened in the Corn Belt, homesteads that rely on personal wells might require treatment systems, increasing their energy consumption for their water.
Wastewater streams from hydraulic fracturing of shales contain much higher levels of total dissolved solids than most wastewater treatment plants can handle.3B. D. Lutz, A. N. Lewis, and M. W. Doyle, “Generation, transport, and disposal of wastewater associated with Marcellus Shale gas development,” Water Resources Research 49 (2013), 647–656. Disposal requires energy to remove wastewater to disposal sites or specialized industrial wastewater treatment facilities at a great distance, to recycle and reuse the water in subsequent wells on site, and to treat the wastewater with new equipment.