Safe and clean drinking water and sanitation is vital to health, child development and social and economic progress – representing a human right.^{1 1}OHCHR and the right to water and sanitationX

As of 2021, a quarter of the global population (2 billion people) use unsafe drinking water sources, while half of humanity (3.6 billion people) live without safely managed sanitation. 1 in 3 people – (2.3 billion) lack basic handwashing facilities at home. For at least 3 billion people, mostly in developing countries, the quality of the water they depend on is unknown because the data is not collected routinely.^{2 2}Summary Progress Update 2021: SDG 6 — water and sanitation for allX

Climate change is a multiplier of health risks and inequalities related to unsafe or insufficient water supplies and poor sanitation. While climate change impacts water availability through changes made to the hydrological system, the impacts of these changes are more likely to be mediated by existing inequalities in water and sanitation management and governance.

Climate change is projected to reduce renewable surface water and groundwater resources significantly in most arid and semi-arid regions. Precipitation variability will increase – leading to growing risks of heavy rainfall and storms, with stronger river flood peaks, higher flood risks and intensified soil erosion, as well as more intense and longer droughts. Climate change is leading to an increase in the frequency and intensity of extreme events, including cyclones, hurricanes, and monsoons, destroying local water and sanitation infrastructure. Sea-level rise is predicted to increase the salinization of coastal aquifers. The temperature rise will lead to increase in evapotranspiration of vegetation, reducing river flows and favouring the concentration of contaminants in water and the biological processes of eutrophication of water bodies.

Impacts on availability, quality, accessibility, affordability and acceptability of water and sanitation

Availability holds that the water supply for each person must be sufficient and continuous for personal and domestic uses. These uses ordinarily include drinking, sanitation, washing of clothes, food preparation, personal and household hygiene. Water availability will be threatened by increased water scarcity and competition for resources.

Quality means that the water required for each personal or domestic use must be safe and free from contaminants that threaten health. Water should be of an acceptable colour, odour and taste for each personal or domestic use. Water quality will decline through overexploitation of groundwater and increased concentration of pollutants.

Accessibility means water facilities and services have to be accessible to everyone without discrimination. Accessibility has four overlapping dimensions: physical accessibility, economic accessibility, non-discrimination, and information accessibility. The accessibility of water and sanitation services will be threatened through widespread damage and infrastructure due to flooding and extreme events.

Affordability means that access to sanitation facilities and services, including construction, emptying and maintenance, must be available at a price that is affordable for all people without limiting their capacity to access other human rights. The affordability of water services may decline as increased competition between uses of water leads to rising costs.

Acceptability means that water and sanitation services must be culturally acceptable. This includes that they should be safe, and ensure privacy and dignity. Under increasing stress, it is likely that the cultural acceptability of water and sanitation services is not prioritized and is in some cases ignored.^{3 3}Special Rapporteur on the human rights to safe drinking water and sanitation. Special Thematic Report 1: Outlining the impacts of climate change on water and sanitation around the worldX