Water quality and inequality

• Author: Philip Davies
• Position: Professor of Water Technology, School of Engineering, University of Birmingham, United Kingdom

About half a billion people presently suffer severe water scarcity all year round, and 1.8 to 2.9 billion people face severe scarcity for several months of the year. By 2025, half of the world’s population will be living in areas experiencing water stress.

By 2025, half of the world’s population will be living in areas suffering water stress. (Photo: Max2611 / iStock / Getty Images Plus)

In terms of quality, the world’s water resources are distributed inconveniently. Most water (97.5 percent) sits in the oceans, and is much too salty to drink. Good quality surface water constitutes less than one-half a percent of the world’s water resources. Between these two extremes, there are other sources of water, such as groundwater, which, in many locations, is too saline to consume without treatment, and industrial waste streams, which may contain a broad range of natural and man-made pollutants.

Areas most vulnerable to water stress are those where demands for drinking and irrigation exceed natural replenishment from rainfall. These include desert regions (roughly between the latitudes of 15 and 45 degrees), especially in the Northern hemisphere. The countries in these regions have varying capacities to build infrastructure such as dams, pipelines and desalination plants.

Since much more water is needed for agriculture than for direct consumption, the economic capacity to import food is also an important factor. Currently, countries like Kuwait or Qatar, which have virtually no natural renewable water supply, get around this problem by desalinating water for drinking and importing food. Meanwhile countries like Somalia and Yemen, which have weak economies and challenging political landscapes, face severe water scarcity and suffer from catastrophic water shortages. In terms of forecasts, the hotspots of increasing water scarcity include Egypt, Pakistan, India and North and North West China.

Seawater desalination is an attractive option for increasing water supply to a large proportion of the world’s water-stressed populations. Thanks to technological innovations, the capacity of desalination plants to produce freshwater has increased significantly and the energy consumption in seawater desalination over the last 20 years has almost halved, making it a lot more affordable. (Photo: PhotoStock-Israel / Alamy Stock Photo)

Coastal desalination plants

Civilizations tended to evolve along coastlines. This means that seawater desalination is an attractive...