From 8-12 December 2025, the city of Bangkok, Thailand, hosted the IWA Water and Development Congress, welcoming over 2,000 delegates from 95 countries. The congress brought together a broad and diverse audience, including academic researchers, water utilities, industry representatives, technology developers, international organisations, non-governmental organisations, and policymakers, alongside a large exhibition showcasing innovations in water and sanitation technologies.

Dr Tania Gomez was invited to deliver a short presentation during the workshop “The Science You Need to Understand Emissions from Non-Sewered Sanitation”. Her presentation focused on methane and greenhouse gas emissions from septic tanks, drawing on findings from the Decentralised Water Technologies (DWT) project. This contribution formed part of a suite of three presentations highlighting recent greenhouse gas (GHG) measurements from non-sewered sanitation systems across different global contexts.

The workshop, organised by Dr Linda Strande, Prof Caetano Dorea and Prof Barbara Evans, attracted more than 30 participants and facilitated in-depth discussion on the scientific and methodological challenges associated with quantifying GHG emissions from non-sewered sanitation systems (NSSS). Key themes included the lack of standardised measurement protocols, uncertainties in existing datasets, and the implications of assumptions currently used by international bodies such as the IPCC when estimating emissions from these systems.

These discussions are particularly relevant given that non-sewered sanitation systems remain one of the most widely implemented sanitation solutions in the Global South, including large parts of Asia. Importantly, NSSS are also prevalent in the Global North; for example, over 200,000 septic systems are currently installed in Scotland, where emissions from wastewater treatment infrastructure are still poorly quantified. The workshop highlighted the urgent need for improved measurement, reporting and integration of emissions from non-sewered systems into national and international climate accounting frameworks.