Recommended Citation: WWQA, 2024. Technical Brief – The role of citizen science in improving ambientwater quality - Sustainable Development Target 6.3. Published by Earthwatch Europe on behalf of the United Nations Environment Programme-coordinated World Water Quality Alliance. July 2024.DOI: 10.5281/zenodo.12634359 This is the Technical Brief. There is an accompanying Policy Brief (DOI: 10.5281/zenodo.12650972). Key message: International recognition of the need for global action on water is building. In 2023 the UN Water Conference made it clear that water is essential for the achievement of the Sustainable Development Goals, and for the health and prosperity of people and planet. But that progress on water related goals and targets remains alarmingly off track. The 2024 United Nations Environment Assembly (UNEA 6) resolution on Effective and inclusive solutions for strengthening water policies - (UNEP/EA.6/L.13) makes clear that the collection of water quality data needs to be enhanced and used for evidence-based decision making and informed water resource management. Despite the awareness that good ambient water quality is crucial for human survival, it is alarming how little information about the quality of water in lakes, rivers, and groundwater is available globally. Urgent action needs to be taken if we want to understand and protect our water supplies. This brief calls for international policy makers and local communities to work together to monitor and improve water quality using a readily available approach – citizen science. Without immediate adoption, the authors believe that Sustainable Development Target 6.3 will not be met.