Editing IPCC:AR6/WGII/Chapter-6 (section)

==== 6.3.5.6 Water and Sanitation ====

<div id="h3-33-siblings" class="h3-siblings"></div>

Adaptation to water scarcity can be through measures to increase supply (e.g., water storage, rainwater harvesting, desalination, river basin transfers, increased abstraction, reduced pollution of water sources), or manage demand (e.g., reduce leakage lower consumption, use of water efficiency devices, greywater reuse, behaviour change). A combination of these measures is usually required (e.g., Ives, Simpson and Hall, 2018; Dirwai et al., 2021; Wang et al., 2018a). Reliable and well-adapted water and sanitation services support economic growth, public health, reduce marginalisation and poverty, and can lower energy use and improve water quality ( [[#Campos--2015|Campos and Darch, 2015]] ; [[#Miller--2017|Miller and Hutchins, 2017]] ; Jeppesen et al., 2015; Hamiche, Stambouli and Flazi, 2016).

Globally, water sector adaptation costs are estimated to be USD 20 billion yr -1 by 2050 (Fletcher, Lickley and Strzepek, 2019). Globally, the budget required by 2030 for water infrastructure (new and refurbishment) is more than half of the budget required for all infrastructure ( [[#Koop--2017|Koop and van Leeuwen, 2017]] ). For OECD countries, water adaptation increases costs by 2%, but this proportion is far higher for developing nations ( [[#Olmstead--2014|Olmstead, 2014]] ).

A number of adaptation actions are available to reduce the impacts of floods on water and sanitation infrastructure. Active management reduces blockages in water infrastructure and protects related services such as roads and culverts which are essential to ensure the operation of onsite sanitation infrastructure (Capone et al., 2020). The impact of floods for onsite or sewerage systems can be lowered by reducing or eliminating excreta from the environment through regular maintenance, cleaning and clearing of blockages ( [[#O’Donnell--2020|O’Donnell and Thorne, 2020]] ; Borges Pedro et al., 2020).

Infrastructure to protect key assets such as water and wastewater treatment plants or pumping stations has a high cost but benefits all connected households and reduces pollution from flood events. In well-regulated water sectors, there has been an increasing focus on such investments ( [[#Campos--2015|Campos and Darch, 2015]] ). Whereas more diffused cheaper interventions can reduce flood water ingress to domestic toilets (Irwin et al., 2018). [[#Luh--2017|Luh et al. (2017)]] found that protected dug wells were one of the least resilient technologies, whereas piped, treated, utility managed surface water systems had higher resilience.

Protecting water sources from pollution is even more important in a warmer climate that increases the frequency of algal blooms. Individual assets such as water intake pipes can be protected using screens (Kim et al., 2020a), whereas basin-scale land management is required to reduce nutrient load from runoff (Me et al., 2018), whilst injecting water or installing barriers can protect coastal aquifers from salinisation ( [[#Siegel--2020|Siegel, 2020]] ).

More radical structural interventions may be needed in the longer term, but would need to be planned and delivered in coordination with investments in other sectors, particularly housing (Lüthi, Willetts and Hoffmann, 2020). As an interim measure, sanitation services with a lower reliance on fixed infrastructure, or container-based sanitation could be appropriate in many urban areas that are badly affected by flooding (Mills et al., 2020).

Other actions include use of adaptive planning (Evans, Rowell and Semazzi, 2020), integration of measures of climate resilience into water safety plans (Prats et al., 2017), as well as improved accounting and management of water resources (Lasage et al., 2015). Policy prescriptions on technologies for service delivery and changes in management models offer potential to reduce risks, particularly in low-income settings (Howard et al., 2016). Where formal sewerage provision is lacking, community based adaptation that incorporates both the function of the sanitation system and the vulnerability of users (e.g., women, children, elderly, ill or disabled) into the design is essential ( [[#Duncker--2019|Duncker, 2019]] ).

<div id="6.3.5.7" class="h3-container"></div>

<span id="flood-management"></span>