Climate Change Impacts on Urban Sanitation: A Systematic Review and Failure Mode Analysis

Assessment of sanitation infrastructure resilience to extreme rainfall and flooding: Evidence from an informal settlement in Kenya

Sanitation infrastructure can fail during heavy rainfall and flooding, allowing the release of fecal waste - and the pathogens it carries - into spaces where people live, work, and play. However, there is a scarcity of reliable frameworks that can effectively assess the resilience of such infrastructure to extreme rainfall and flooding events. The purpose of this study was to develop and apply a novel framework for assessing and ranking the resilience of sanitation infrastructure in informal settlements. A framework for assessing sanitation infrastructure resilience was developed consisting of 19 indicators that were categorized into three domains: physical infrastructure design (8 indicators), operations and management (5 indicators), and environmental factors (6 indicators). The framework was applied to data from 200 shared sanitation facilities in Kibera, Kenya, collected through transect walks, field observations, surveys, and sanitary risk inspections. Results indicate that sanitation infrastructure type impacts resilience. Toilet facilities connected to a piped sewer (r = 1.345, 95% CI: 1.19-1.50) and toilets connected to a septic system (r = 1.014, 95% CI: 0.78-1.25) demonstrated higher levels of resilience compared to latrines (r = 0.663, 95% CI: 0.36-0.97) and hanging toilets (r = 0.014, 95% CI: 0.30-0.33) on a scale ranging from 0 to 4. The key determinants of sanitation infrastructure resilience were physical design, functionality, operational and maintenance routines, and environmental factors. This evidence provides valuable insights for developing standards and guidelines for the design and safe siting of new sanitation infrastructure and encourages investment in sewer and septic systems as superior options for resilient sanitation infrastructure. Additionally, our findings underscore the importance for implementers and communities to prioritize repairing damaged infrastructure, sealing potential discharge points into open drains, and emptying filled containment systems before the onset of the rainy season.

Urban Sanitation: New Terminology for Globally Relevant Solutions?

Progress toward Sustainable Development Goals for global access to safe sanitation is lagging significantly. In this Feature, we propose that misleading terminology leads to errors of categorization and hinders progress toward sanitation service provision in urban areas. Binary classifications such as "offsite/onsite" and "sewered/nonsewered" do not capture the need for "transport to treatment" or the complexity of urban sanitation and should be discarded. "Fecal sludge management" is used only in the development context of low- or middle-income countries, implying separate solutions for "poor" or "southern" contexts, which is unhelpful. Terminology alone does not solve problems, but rather than using outdated or "special" terminology, we argue that a robust terminology that is globally relevant across low-, middle-, and upper-income contexts is required to overcome increasingly unhelpful assumptions and stereotypes. The use of accurate, technically robust vocabulary and definitions can improve decisions about management and selection of treatment, promote a circular economy, provide a basis for evidence-based science and technology research, and lead to critical shifts and transformations to set policy goals around truly safely managed sanitation. In this Feature, the three current modes of sanitation are defined, examples of misconceptions based on existing terminology are presented, and a new terminology for collection and conveyance is proposed: (I) fully road transported, (II) source-separated mixed transport, (III) mixed transport, and (IV) fully pipe transported.

Climate change impacts on wastewater infrastructure: A systematic review and typological adaptation strategy

Wastewater infrastructures play an indispensable role in society's functioning, human production activities, and sanitation safety. However, climate change has posed a serious threat to wastewater infrastructures. To date, a comprehensive summary with rigorous evidence evaluation for the impact of climate change on wastewater infrastructure is lacking. We conducted a systematic review for scientific literature, grey literature, and news. In total, 61,649 documents were retrieved, and 96 of them were deemed relevant and subjected to detailed analysis. We developed a typological adaptation strategy for city-level decision-making for cities in all-income contexts to cope with climate change for wastewater structures. 84% and 60% of present studies focused on the higher-income countries and sewer systems, respectively. Overflow, breakage, and corrosion were the primary challenge for sewer systems, while inundation and fluctuation of treatment performance were the major issues for wastewater treatment plants. In order to adapt to the climate change impact, typological adaptation strategy was developed to provide a simple guideline to rapidly select the adaptation measures for vulnerable wastewater facilities for cities with various income levels. Future studies are encouraged to focus more on the model-related improvement/prediction, the impact of climate change on other wastewater facilities besides sewers, and countries with low or lower-middle incomes. This review provided insight to comprehensively understand the climate change impact on wastewater facilities and facilitate the policymaking in coping with climate change.

Burden of disease attributable to unsafe drinking water, sanitation, and hygiene in domestic settings: a global analysis for selected adverse health outcomes

BACKGROUND

Assessments of disease burden are important to inform national, regional, and global strategies and to guide investment. We aimed to estimate the drinking water, sanitation, and hygiene (WASH)-attributable burden of disease for diarrhoea, acute respiratory infections, undernutrition, and soil-transmitted helminthiasis, using the WASH service levels used to monitor the UN Sustainable Development Goals (SDGs) as counterfactual minimum risk-exposure levels.

METHODS

We assessed the WASH-attributable disease burden of the four health outcomes overall and disaggregated by region, age, and sex for the year 2019. We calculated WASH-attributable fractions of diarrhoea and acute respiratory infections by country using modelled WASH exposures and exposure-response relationships from two updated meta-analyses. We used the WHO and UNICEF Joint Monitoring Programme for Water Supply, Sanitation and Hygiene public database to estimate population exposure to different WASH service levels. WASH-attributable undernutrition was estimated by combining the population attributable fractions (PAF) of diarrhoea caused by unsafe WASH and the PAF of undernutrition caused by diarrhoea. Soil-transmitted helminthiasis was fully attributed to unsafe WASH.

FINDINGS

We estimate that 1·4 (95% CI 1·3-1·5) million deaths and 74 (68-80) million disability-adjusted life-years (DALYs) could have been prevented by safe WASH in 2019 across the four designated outcomes, representing 2·5% of global deaths and 2·9% of global DALYs from all causes. The proportion of diarrhoea that is attributable to unsafe WASH is 0·69 (0·65-0·72), 0·14 (0·13-0·17) for acute respiratory infections, and 0·10 (0·09-0·10) for undernutrition, and we assume that the entire disease burden from soil-transmitted helminthiasis was attributable to unsafe WASH.

INTERPRETATION

WASH-attributable burden of disease estimates based on the levels of service established under the SDG framework show that progress towards the internationally agreed goal of safely managed WASH services for all would yield major public-health returns.

FUNDING

WHO and Foreign, Commonwealth & Development Office.

Perceptions of Inclusivity and Sustainability in Urban Sanitation in Global South Cities

Citywide Inclusive Sanitation (CWIS) calls for sustainable urban sanitation services for all, but the definitions of "inclusion" and "sustainability" within the framework leave room for interpretation. This study aims to provide an initial understanding of how these terms are currently interpreted by a range of sanitation actors in six cities of the Global South. Urban sanitation professionals from private (n = 16), public (n = 28), non-governmental (n = 43), and academic (n = 10) institutions were interviewed using a standardized tool, and data was analyzed to identify themes and trends. Terms such as "everyone" or "for all" shed little light on how to ensure inclusion, though disabled people, women, children, and the poor were all highlighted when probed. Greater specificity of beneficiary groups in policy is likely to enhance their visibility within sanitation service provision. All three pillars of sustainability identified within CWIS were referenced, with different stakeholders focusing more closely on environmental, social, or economic sustainability, based on their organizational goals and interests. Greater collaboration may foster a balanced view across the pillars, with different organizations acting as champions for each one. The findings can facilitate discussions on a shared understanding of multi-stakeholder engagement in achieving inclusive and sustainable sanitation service provision.