Global water scarcity increases due to poor water quality

Increasing water requirements for agriculture, households and industry, combined with changes in water availability due to climate change and more severe droughts, are exacerbating water scarcity worldwide. However, the amount of water available for human use is not the only factor causing water scarcity as water quality also plays a major role. Insufficient access to good quality water resources causes 40% of the world’s population to suffer the consequences of water scarcity. For the first time, new research led by Utrecht University has calculated water scarcity including both water quality and the effects of desalinisation and wastewater treatment and reuse. The results of this research were recently published in the scientific journal Environmental Research Letters.

“About 30 percent of the world’s population deals with severe water scarcity,” says Dr. Michelle van Vliet, assistant professor water scarcity and water quality at Utrecht University, and lead author of the study. “That percentage increases to 40 percent when you also take water quality into account.”

Water for human use

Water use for different sectors depends not only on the amount of water that is available, but also upon the quality of the water being suitable for the intended use. Water scarcity for the energy sector, for example, increases when water temperatures are very high, as this constraints cooling water use for power stations. Similarly, water scarcity increases for agriculture and households when the water is too saline or if other pollutant levels are too high. “Water scarcity is not just a shortage of water, it is a lot more complicated than that,” Van Vliet states.

Water scarcity is particularly influenced by water quality in China and India, where agriculture, households and industries not only use a lot of water, but also contribute to water pollution. “This is mainly a problem in areas where a lot of wastewater is being discharged without any proper treatment, and where a lot of water is directly used again,” says Van Vliet.

What now?

The researchers describe that expanding desalinisation plants, wastewater treatment and reuse within and between sectors can simultaneously increase freshwater supply and decrease water pollution, greatly reducing the number of people affected by water scarcity globally.

The research team used the results of several computer models that calculate water availability, quality and sectoral demands of water. They combined these results with detailed data from more than 15,000 desalinisation plants and estimates of treated wastewater re-use. The authors found that if wastewater reuse is doubled and desalinisation capacity is quadrupled, the number of people affected by severe water scarcity can potentially be decreased from 40% to 14%.

“This is especially effective in Asia, but it is important to keep in mind that desalinisation and treated wastewater reuse need to happen in a sustainable way, and that the waste products of these processes are disposed of properly,” Van Vliet concludes.

Publication

Michelle T.H. van Vliet, Edward R. Jones, Martina Flörke, Wietse H.P. Franssen, Naota Hanasaki, Yoshihide Wada and John R. Yearsley, 2021. Global water scarcity including surface water quality and expansions of clean water technologies, Environmental Research Letters. https://doi.org/10.1088/1748-9326/abbfc3