Perspectives

This Perspective explores the multiscale transport mechanisms of water and solutes in desalination and ion selective membranes, offering mechanistic insights to guide the design of next-generation membranes and nanoporous systems for applications in water purification, separations, and energy technologies.

Quantifying water sustainability relies on limited and non-uniform metrics that risk greenwashing and hinder effective investment decisions. To address this, the proposed water sustainability index (WSI) offers a transparent, quantitative framework that accounts for water withdrawals, discharges, consumption, reuse and watershed stress to guide cost-effective sustainability improvements.

Urban water hazards like flooding and contamination are worsening due to climate change, and their risks are deeply influenced by historical oppression and inequitable infrastructure decisions. This Perspective examines how urban flood risk is inequitably distributed and argues that climate adaptation should prioritize systemic, justice-focused reforms to address both resilience and historic social injustices.

Despite their importance to the Earth system and the well-being of societies, water fluxes occurring below the land surface are poorly constrained observationally and their global estimates remain uncertain. This Perspective proposes a framework that integrates different data sources with conceptual reasoning in order to better understand subsurface water cycling.

Riverine heatwaves have severe consequences for society, the economy and ecosystems and are becoming more frequent with climate change. This Perspective addresses research efforts to better understand, monitor, model and manage these extreme events.

Antimicrobial resistance has evolved over decades due to widespread antimicrobial use, with resistance genes now circulating across humans, animals and the environment, creating complex cross-sector connectivity challenges. This Perspective advocates for genomics-based studies of AMR connectivity to enable coordinated global action and investment under the One Health framework.

Wastewater-based epidemiology has already proven to be a powerful tool to monitor the spread of a number of diseases. This Perspective discusses the integration with machine learning, highlighting its potential in a number of wastewater-based epidemiology applications.

This Perspective leverages waterbirds to establish a conceptual foundation for studying wildlife interactions with floating photovoltaics (FPVs), highlighting five key considerations to guide future research on FPV–wildlife interactions.

This Perspective proposes strategies to develop and implement heterogeneous catalytic technologies for efficient PFAS mineralization.

Despite considerable attention, hygiene systems and practices remain inadequate where they are most needed. New thinking and innovative approaches are needed to develop, implement and evaluate hygienic systems to reduce pathogen exposure in high-transmission settings.

This Perspective highlights the uncertainties in assessing future drought severity, arising from conceptual misconceptions, methodological discrepancies and the limitations of Earth system models (ESMs) in accurately representing hydrological and ecological processes. A balanced approach that incorporates atmospheric drought indices can better improve the accuracy of drought assessments.

Despite their substantial contributions to watershed resilience, headwater streams are becoming increasingly imperilled. This Perspective summarizes the status of headwater streamflow information and proposes guidance for advancing the understanding of headwater hydrology to support better management of these systems.

Concern about the potential health and environmental hazards of substances known as PFAS have led to strong regulations, especially in Europe and the United States. This Perspective examines whether early warnings were followed and whether lessons can be learned from the way the chemicals were dealt with since their discovery.

This Perspective presents a wetting regime framework that is classified by dominant hydrologic mechanisms and highlights the resulting responses of stream biogeochemistry and community ecology.

This Perspective proposes a way to design membranes to separate ions of similar size and charge with a view to their use in resource recovery, water reuse and energy storage technologies.

This Perspective reviews the current understanding of groundwater recharge by meltwater, discusses the scales at which cryosphere–groundwater interactions are relevant, identifies key cryo-hydrogeological processes that need further study, and emphasizes the critical importance of these interactions for current and future water availability in mountain regions.

This study addresses the limitations and constraints of flood adaptation. These limits could result in a growing ‘adaptation gap’ (the difference between actual and desirable flood risk), leading to unbearable risks and pushing communities in flood zones into retreat.

The potential hazard of per- and polyfluoroalkyl substances has led to new regulations affecting requirements for water quality. This Perspective proposes a protocol to adapt water treatment technology to meet new regulation requirements.

Access to sanitation is a fundamental right that is still missing, especially in many parts of low-income countries. This Perspective focuses on the impact of unclean school latrines on child health.

Efficiency is only one of the parameters involved in solar evaporation that should be improved to make it practical. Depending on the application, various factors of merit should be taken into consideration, as discussed in this Perspective.