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Water scarcity and the resilience of global water systems

Author: Fabiola Branz, Assistant Controller Europe, Xylem

Published: 23 Aug 2021

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Water security is key in order to address the challenges of climate change and reduce carbon emissions in the energy sector, agriculture, forestry and transportation.

The demand of freshwater has increased significantly in the past 100 years and is currently increasing in particular in emerging economies and lower income countries as a result of growing population and economic development. Food demand will also increase exponentially and so irrigated food production, which, according to the Food and Agriculture Organization (FAO), will increase by 50% by 2050.

This will necessarily require improvement in water systems and usage efficiency.

According to the UN, currently over two billion people live in countries experiencing water stress and an estimated four billion people live in areas that suffer from severe physical water scarcity for at least one month per year. According to the International Water Management Institute (IWMI) about 1.6 billion people face economic water scarcity, where a lack of water infrastructure prevents the access to water which would be otherwise available.

The widespread decline in global water storage and freshwater availability are primarily due to intensive extraction of groundwater and an increasing temperature-induced surface water loss. Reservoir expansion has not been able to keep pace with population growth and storage capacity of existing reservoirs is decreasing due to sedimentation.

Moreover pollution and climate change contribute to severe water depletion and scarcity. Many existing worldwide aquifers and groundwater systems are under considerable stress, and water quality has deteriorated as a result of pollution in nearly all major rivers in Africa, Asia and Latin America. According to the World Water Assessment Programme by UNESCO, it is estimated that 80% of all industrial and municipal wastewater is released into the environment without any prior treatment, this ratio being much higher in least developed countries, where sanitation and wastewater treatment facilities are scarce. In addition, climate change is expected to create a more unreliable water supply, escalating the problem of water shortage in already affected areas and potentially also in areas where it was not an issue before.

In the face of those intensifying challenges, resilience of water infrastructure is crucial like never before. Resilience is the capacity to avoid or recover quickly from stresses or shocks, and to continue to deliver both under normal and extraordinary circumstances, while avoiding major system failures. New and better hydraulic infrastructure will also be needed to meet the increasing demand, in particular in developing countries. It is estimated by the Organization for Economic Co-operation and Development (OECD) that by 2030, investment in water and sanitation infrastructure will need to be around US$0.9–1.5 trillion per year – roughly 20% of the total investment in all types of infrastructure – and will need to be mainly concentrated in the Southern hemisphere.

Globally, water storage infrastructure is ageing, not only in the poorer countries but also in the developed world. It is estimated that in the US there is a water main break every two minutes and an estimated 22 billion liters of treated water is lost each day. The U.S. Environmental Protection Agency (EPA) announced in 2021 a $6.5 billion investment in new funding for water infrastructure projects, which should alleviate the problem. Europe’s water infrastructure is also ageing in all EU member states. Investment in water infrastructure is not keeping pace with the challenges we are facing, the growing population, urbanization and climate change. The EU would need to double its annual investment of €45 billion in order to modernize the existing infrastructure (Euractiv).

An important aspect of water infrastructure and resilience is the current status of dams globally. According to the International Commission on Large Dams (ICOLD, 2020), dams are used for irrigation, hydropower, water supply, flood control, and recreation. The construction of large dams peaked in the 1960s/70s, especially in Asia, Europe, and North America. Since then global dam construction has slowed down dramatically due to concerns about their environmental and social impact, but also as a result of emerging alternative types of water storage and energy sources. The decline is more manifest in North America, whilst there has been an increase in Asia, Africa and South America in the past 50 years.

Thousands of large dams built in the middle of the previous century have or will soon reach the threshold of 50 years and many are approaching 100 years (an average life expectancy of a dam is 50 years), particularly in North America and in Europe. Older dams combined with poor maintenance represent a higher risk to public safety, particularly for downstream areas. As such dam decommissioning has been a growing phenomenon in recent years and has become quite common in the USA and Europe, in situations where economic and practical limitations prevent a dam from being upgraded or if its original use has become obsolete. Decommissionig large dams is an extremely complex and lengthy process over many years, and often requires constant expert and public input.

In developed nations where water availability is more predictable, many ageing dams have become obsolete, and their decommissioning represents the best option to deal with ageing infrastructure, thus resulting in cost efficiency and positive ecological impact. However, dams may still represent critical infrastructure for low-income countries to provide clean water and sanitation, irrigation and poverty alleviation, by providing a reliable, clean energy source.


The global issue of water scarcity is often under-represented and under-discussed. However, it is crucial that water scarcity is part of the overall fight against climate change. There are many reasons behind water stress, climate change being one, but other causes are increasing population, higher economic activity and more pollution. Adding to this, the current status of the global water infrastructure is deteriorating and significant investment will be needed to upgrade the system to cope with increasing demand and lower availability of fresh water. There is an obvious disparity between rich countries and developing nations, however the ageing infrastructure is also very much affecting the USA and Europe.

*The views expressed are the author’s and not ICAEW’s.