Tackling water pollution can prevent future water scarcity, say researchers in the Netherlands, but too often the focus is on water quantity.

Global water scarcity is one of the challenges to achieving the UN Sustainable Development Goals (SDGs). Indeed, more than half of the world's population lives in areas where water is limited and/or over-polluted.

This poses a challenge to the balance between water supply and demand and causes economic risk for sectors using water, including energy, agriculture, households and industry. Based on investigations into the Pearl (Zhujiang) River basin in China, the team from Wageningen University & Research (WUR) argue that managing water quality is a low-cost way to halve future water scarcity.

The challenge is to address water scarcity in a cost-effective manner to ensure sufficient water of good quality to meet human, ecological, social and economic needs and support sustainable development, says Maryna Strokal, assistant professor at WUR's water systems and global change group.

"Many researchers often focus on water scarcity by looking only at water quantity and not quality," she said. "Options for water quantity are more expensive.

"Investing in reducing water pollution is cost-effective to reduce future water scarcity. We looked at this for the Pearl River Basin in China. But similar lessons can be drawn for other river basins facing water pollution and water scarcity.

With colleagues from the International Institute for Applied Systems Analysis and Utrecht University, Strokal integrated knowledge, indicators and modelling tools.

"With this new integrative approach, we were able to estimate the costs of reducing water scarcity under different socioeconomic and climate scenarios for 2050. We looked at water quality management options such as saving chemical fertilisers and treating waste and at water quantity options such as water storage and water-saving techniques," she added.

"The results of the study show that future water scarcity in 2050 is expected to increase by a factor of four in most parts of the Pearl River Basin, under a scenario with high economic development and global warming. The results also show that water quality management options can cost-effectively halve future water scarcity.

"Our analysis can serve as an example for water scarcity assessment for other highly pressurised and polluted river basins around the world and inform the design of cost-effective measures to reduce water scarcity."

The paper is published in Nature Communications journal.