Editing IPCC:AR6/WGII/Chapter-4 (section)

=== 4.6.4 Adaptation in the Water, Sanitation and Hygiene Sector ===

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AR5 pointed to adaptive water management techniques ( ''limited evidence, high agreement'' ) ( [[#Field--2014b|Field et al., 2014b]] ), while SR1.5 documented the need for reducing vulnerabilities and promoting sustainable development and disaster risk reduction synergies ( ''high confidence'' ) ( [[#IPCC--2018a|IPCC, 2018a]] ). WaSH has also been identified as a low-regrets adaptation measure ( [[#Cutter--2012|Cutter et al., 2012]] ).

Access to appropriate, reliable WaSH protects against water-related diseases, particularly after climate hazards such as heavy rainfalls and floods ( [[#Carlton--2014|Carlton et al., 2014]] ; [[#Jones--2020|Jones et al., 2020]] ). WaSH interventions have been demonstrated to reduce diarrhoea risk by 25–75% depending on the specific intervention ( [[#Wolf--2018|Wolf et al., 2018]] ) ( ''high confidence'' ). Conversely, inadequate WaSH is associated with an estimated annual loss of 50 million daily adjusted life years ( [[#Prüss-Ustün--2019|Prüss-Ustün et al., 2019]] ), of which 89% of deaths are due to diarrhoea, and 8% of deaths from acute respiratory infections ( [[IPCC:Wg2:Chapter:Chapter-7|Chapter 7]] WGII 7.3.2), making universal access to WaSH (i.e., achievement of SDG 6.1, 6.2) a critical adaptation strategy ( ''high confidence'' ). However, not all WaSH solutions are suited to all climate conditions ( [[#Sherpa--2014|Sherpa et al., 2014]] ; [[#Howard--2016|Howard et al., 2016]] ), so health outcome improvements are not always sustained under changing climate impacts ( [[#Dey--2019|Dey et al., 2019]] ) ( ''medium evidence, high agreement'' ). As such, WaSH infrastructure also needs to be climate-resilient ( [[#Smith--2015|Smith et al., 2015]] ; [[#Shah--2020|Shah et al., 2020]] ). In addition to new WaSH infrastructure design and implementation, expansion and replacement of existing infrastructure offer opportunities to implement climate-resilient designs and reduce greenhouse emissions ( [[#Boholm--2017|Boholm and Prutzer, 2017]] ; [[#Dickin--2020|Dickin et al., 2020]] ) ( ''medium evidence, high agreement'' ).

Effective adaptation strategies include protecting source water and managing both water supply and demand. Source water protection ( [[#Shaffril--2020|Shaffril et al., 2020]] ) has proven effective in reducing contamination. Improved integrated (urban) water resources management ( [[#Kirshen--2018|Kirshen et al., 2018]] ; [[#Tosun--2019|Tosun and Leopold, 2019]] ) and governance ( [[#Chu--2017|Chu, 2017]] ; [[#Miller--2020|Miller et al., 2020]] ) and enhanced ecosystem management ( [[#Adhikari--2018b|Adhikari et al., 2018b]] ) lead to policies and regulations that reduce water insecurity and, when developed appropriately, reduce inequities ( ''medium confidence'' ). Supply (source) augmentation, including dams, storage and rainwater/fog harvesting, can increase the supply or reliability of water for drinking, sanitation and hygiene ( [[#DeNicola--2015|DeNicola et al., 2015]] ; [[#Pearson--2015|Pearson et al., 2015]] ; [[#Majuru--2016|Majuru et al., 2016]] ; [[#Poudel--2017|Poudel and Duex, 2017]] ; [[#Lucier--2018|Lucier and Qadir, 2018]] ; [[#Goodrich--2019|Goodrich et al., 2019]] ) ( ''high confidence'' ). For example, rainwater harvesting in an Inuit community increased water for hygiene by 17%, reduced water retrieval efforts by 40% and improved psychological and financial health (Mercer and [[#Hanrahan--2017|Hanrahan, 2017]] ). However, climate change impacts will affect amounts of rainwater available. A recent study concluded that domestic water demand met through rainwater harvesting generally improves under climate change scenarios for select communities in Canada and Uganda, with the exception of drier summers in some areas of Canada ( [[#Schuster-Wallace--2021|Schuster-Wallace et al., 2021]] ). Further, it is important to recognise that many of these interventions require financial investments that make them inaccessible to the poorest ( [[#Eakin--2016|Eakin et al., 2016]] ). Demand for water can be decreased through reductions in water loss from the system (e.g., pipe leakage) ( [[#Orlove--2019|Orlove et al., 2019]] ) and water conservation measures ( [[#Duran-Encalada--2017|Duran-Encalada et al., 2017]] ) ( ''medium confidence'' ).

During periods of water insecurity, people often implement maladaptive strategies ( [[#Magnan--2016|Magnan et al., 2016]] ), that is, strategies that can increase the risk of adverse health impacts, increase exposure to violence or cause malnutrition ( [[#Kher--2015|Kher et al., 2015]] ; [[#Pommells--2018|Pommells et al., 2018]] ; [[#Collins--2019a|Collins et al., 2019a]] ; [[#Schuster--2020|Schuster et al., 2020]] ) ( ''medium evidence, high agreement'' ). Examples include walking further, using less safe water sources, prioritising drinking and cooking over personal/household hygiene, or reducing food/water intake. Conversely, some rebalancing of gender roles can occur when women and girls cannot source sufficient water, with men building additional water supply or storage infrastructure or fetching water ( [[#Singh--2015|Singh and Singh, 2015]] ; [[#Magesa--2016|Magesa and Pauline, 2016]] ; [[#Shrestha--2019b|Shrestha et al., 2019b]] ). Some adaptation strategies create unintended health threats such as increased odds (1.55) of mosquito larvae in water storage pots ( [[#Ferdousi--2015|Ferdousi et al., 2015]] ), which could have even more significant impacts in the future given projected range expansion for vectors as a result of climate change ( [[#Liu-Helmersson--2019|Liu-Helmersson et al., 2019]] ). Other unintended consequences include pathogen contamination ( [[#Gwenzi--2015|Gwenzi et al., 2015]] ) and time or financial trade-offs ( [[#Schuster--2020|Schuster et al., 2020]] ) ( ''medium evidence, high agreement'' ). Wastewater reuse for irrigation may have adverse health impacts if wastewater is not treated ( [[#Dickin--2016|Dickin et al., 2016]] ). Conversely, especially where women are responsible for domestic and productive water management, adaptive agricultural water strategies, such as water-efficient irrigation or low-water crops, mean that less water from finite water supplies are used for agriculture, leaving more water locally available for domestic purposes (see section 4.6.2). These co-benefits across sectors become important community water stress adaptations ( [[#Chinwendu--2017|Chinwendu et al., 2017]] ), with water savings from one use leading to more water available for other uses. This can reduce domestic water burdens and, therefore, gender inequities ( [[#4.8.3|Section 4.8.3]] ) ( ''limited evidence, high agreement'' ). Further analyses of co-benefits, particularly employing a gender lens, are required to improve adaptation strategies ( [[#McIver--2016|McIver et al., 2016]] ).

In summary, ensuring access to climate-resilient WaSH infrastructure and practices represents a key adaptation strategy that can protect beneficiaries against water-related diseases induced by climate change ( ''high confidence'' ). Better management of water resources, supply augmentation and demand management are important adaptation strategies ( ''high confidence'' ). Reliable, safe drinking water reduces adverse physical and psychological impacts of climate-related water stress and extreme events ( ''robust evidence, medium agreement'' ). WaSH infrastructure expansion and replacement provide opportunities to redesign and increase resilience in rural and urban contexts ( ''limited evidence, high agreement'' ).

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'''Box 4.4 | COVID-19 Amplifies Challenges for WaSH Adaptation'''
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While COVID-19 is an airborne disease (see Cross-Chapter Box COVID in Chapter 7), public health responses to the COVID-19 pandemic and the associated socioeconomic and environmental impacts of these measures intersect with WaSH ( [[#Armitage--2020a|Armitage and Nellums, 2020a]] ). Notably, COVID-19 and climate change act as compound risks in the context of water-induced disasters, exacerbating existing threats to sustainable development ( [[#Neal--2020|Neal, 2020]] ; Pelling et al. 2021).

The principal WaSH response to COVID-19 relates to hand hygiene, an infection control intervention that requires access to sufficient, clean and affordable water beyond cooking, hydration and general sanitation needs, as outlined in SDG6 ( [[#Armitage--2020a|Armitage and Nellums, 2020a]] ). However, despite significant progress, more than 800 million people in central and southern Asia, and 760 million in sub-Saharan Africa, lack basic hand-washing facilities in the home (UNICEF, 2020). Notably, one in four healthcare facilities in select low- and middle-income countries lacks basic water access, and one in six lacks hand-washing facilities ( [[#WHO--2019|WHO, 2019]] ) ( [[#4.3.3|Section 4.3.3]] ). Moreover, household water insecurity also impacts marginalised and minority groups in the Global North ( [[#Deitz--2019|Deitz and Meehan, 2019]] ; [[#Rodriguez-Lonebear--2020|Rodriguez-Lonebear et al., 2020]] ; [[#Stoler--2021|Stoler et al., 2021]] ).

Compound disasters have arisen due to either the co-occurrence of drought, storms or floods and COVID-19. COVID-19 acts as a stress multiplier for women and girls in charge of water collection and minorities and disabled people who are not engaged in water management ( [[#Phillips--2020|Phillips et al., 2020]] ; [[#Rodriguez-Lonebear--2020|Rodriguez-Lonebear et al., 2020]] ). Across the world, existing inequalities deepened due to lockdowns, which further limited access to clean water and education for women and girls, and reinstated gendered responsibilities of child, elderly and sick care, which had been previously externalised ( [[#Cousins--2020|Cousins, 2020]] ; [[#Neal--2020|Neal, 2020]] ; [[#Zavaleta-Cortijo--2020|Zavaleta-Cortijo et al., 2020]] ). Accordingly, COVID-19 has further steepened the path to reach SDGs 2, 3, 4, 5 and 11 ( [[#Lambert--2020|Lambert et al., 2020]] ; [[#Mukherjee--2020|Mukherjee et al., 2020]] ; [[#Neal--2020|Neal, 2020]] ; [[#Pramanik--2021|Pramanik et al., 2021]] ). In addition, the pandemic exacerbated food insecurity in drought-affected eastern and southern Africa ( [[#Phillips--2020|Phillips et al., 2020]] ; [[#Mishra--2021|Mishra et al., 2021]] ). As the twin risk of COVID-19 and hurricanes on the US Gulf Coast ( [[#Pei--2020|Pei et al., 2020]] ; [[#Shultz--2020|Shultz et al., 2020]] ) and cyclone Amphan in Bangladesh ( [[#Pramanik--2021|Pramanik et al., 2021]] ) showed, increased hand washing, additional WaSH and evacuation and shelter infrastructures proved essential for preventing further spread of COVID-19 ( [[#Baidya--2020|Baidya et al., 2020]] ; [[#Ebrahim--2020|Ebrahim et al., 2020]] ; [[#Guo--2020|Guo et al., 2020]] ; [[#Mukherjee--2020|Mukherjee et al., 2020]] ; [[#Pei--2020|Pei et al., 2020]] ; [[#Shultz--2020|Shultz et al., 2020]] ; [[#Pramanik--2021|Pramanik et al., 2021]] ). Moreover, while immediate steps can be taken during disaster response to minimise climate-attributable loss of life, climate adaptation requires long-term strategies that intersect with pandemic preparedness ( [[#Phillips--2020|Phillips et al., 2020]] ).

Public health responses to COVID-19 geared towards infection control and caring for the sick can trigger increased water demand where population numbers and density are high ( [[#Mukherjee--2020|Mukherjee et al., 2020]] ; [[#Sivakumar--2021|Sivakumar, 2021]] ). As COVID-19 has highlighted the importance of WaSH ( [[#4.3.3|Section 4.3.3]] ), this pandemic could also result in long-term positive outcomes in community resilience, improved infection control and health protection while addressing longer-term environmental challenges of climate change ( [[#Phillips--2020|Phillips et al., 2020]] ).

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