Science-Policy Blind Spots and Challenges in Wastewater Infrastructure Regulation under Climate Change

Wastewater infrastructure is essential to environmental protection and public health, yet the regulatory frameworks that govern its design and operation were developed under assumptions of stable climatic and hydrological conditions. Climate change, including sea level rise, salt water intrusion, altered groundwater regimes, intense rainfall, more frequent flooding, prolonged droughts, and shifting soil and precipitation patterns, now challenges these assumptions. Although the vulnerability of large centralised wastewater systems is increasingly recognised, decentralised systems such as septic tanks and soil-based infiltration systems remain largely absent from climate focused regulatory and governance discussions.

This study examines how climate related risks are addressed in decentralised wastewater infrastructure regulation across coastal, suburban, rural and remote inland contexts, with particular attention to governance arrangements and policy design. The analysis shows that regulatory approaches for decentralised systems often rely on static technical criteria that do not reflect dynamic climate driven changes in groundwater levels, soil moisture, flooding patterns, drought severity, or salinity. As a result, regulatory compliance may no longer ensure long term system performance or adequate protection of environmental and public health.

The paper identifies governance factors that limit the translation of scientific understanding into regulatory requirements, including limited forward planning, fragmented institutional responsibilities, limited monitoring of decentralised systems, limited consideration of the receiving environment,  the tendency to treat these systems as private household assets rather than components of critical public infrastructure, and limited support for the communities and householders who own these assets. The analysis highlights the implications of these gaps for climate adaptation and argues for more adaptive and evidence informed regulatory frameworks and surrounding policies to strengthen resilience, environmental protection, and public health.