Water security

Water security has many different aspects: a communal tap for water supply in Soweto, South Africa; residents standing in flood water in Kampala, Uganda; water pollution can lead to eutrophication, harmful algal blooms and fish kills; the town of Farina in South Australia abandoned due to years of drought and dust storms.

The aim of water security is to make the most of water's benefits for humans and ecosystems. The second aim is to limit the risks of destructive impacts of water to an acceptable level.^[1][2] These risks include for example too much water (flood), too little water (drought and water scarcity) or poor quality (polluted) water.^[1] People who live with a high level of water security always have access to "an acceptable quantity and quality of water for health, livelihoods and production".^[2] For example, access to water, sanitation and hygiene services is one part of water security.^[3] Some organizations use the term water security more narrowly for water supply aspects only.

Decision makers and water managers aim to reach water security goals that address multiple concerns. These outcomes can include increasing economic and social well-being while reducing risks tied to water.^[4] There are linkages and trade-offs between the different outcomes.^[3]: 13 Planners often consider water security effects for varied groups when they design climate change reduction strategies.^{[5]: 19–21}

Three main factors determine how difficult or easy it is for a society to sustain its water security. These include the hydrologic environment, the socio-economic environment, and future changes due to the effects of climate change.^[1] Decision makers may assess water security risks at varied levels. These range from the household to community, city, basin, country and region.^[3]: 11

The opposite of water security is water insecurity.^[6]: 5 Water insecurity is a growing threat to societies.^[7]: 4 The main factors contributing to water insecurity are water scarcity, water pollution and low water quality due to climate change impacts. Others include poverty, destructive forces of water, and disasters that stem from natural hazards. Climate change affects water security in many ways. Changing rainfall patterns, including droughts, can have a big impact on water availability. Flooding can worsen water quality. Stronger storms can damage infrastructure, especially in the Global South.^[8]: 660

There are different ways to deal with water insecurity. Science and engineering approaches can increase the water supply or make water use more efficient. Financial and economic tools can include a safety net to ensure access for poorer people. Management tools such as demand caps can improve water security.^[7]: 16 They work on strengthening institutions and information flows. They may also improve water quality management, and increase investment in water infrastructure. Improving the climate resilience of water and hygiene services is important. These efforts help to reduce poverty and achieve sustainable development.^[2]

There is no single method to measure water security.^[8]: 562 Metrics of water security roughly fall into two groups. This includes those that are based on experiences versus metrics that are based on resources. The former mainly focus on measuring the water experiences of households and human well-being. The latter tend to focus on freshwater stores or water resources security.^[9]

The IPCC Sixth Assessment Report found that increasing weather and climate extreme events have exposed millions of people to acute food insecurity and reduced water security. Scientists have observed the largest impacts in Africa, Asia, Central and South America, Small Islands and the Arctic.^[10]: 9  The report predicted that global warming of 2 °C would expose roughly 1-4 billion people to water stress. It finds 1.5-2.5 billion people live in areas exposed to water scarcity.^[10]: 660