Water safety refers to the quality of one’s drinking water and whether it lacks dangerous contaminants. Limited access to safe water is projected to impact approximately 5 billion people worldwide by 2050. Climate change and worsening severe weather events pose increasing threats to global water safety. However, people may not perceive links between climate change and water safety, potentially undermining their willingness to implement behaviors that improve water safety. Existing studies on water safety risk perceptions have mostly been conducted in single-country contexts, which limits researchers’ ability to make cross-national comparisons. Here, we assessed the extent to which people’s severe weather concern and climate change concern predict their water safety concern. Our analyses used survey data from the 142-country 2019 Lloyd’s Register Foundation World Risk Poll, including 21 low-income and 34 lower-middle-income countries. In mixed-effects models, severe weather concern was significantly more predictive of water safety concern than was climate change concern, although both resulted in positive associations. Worldwide, this finding was robust, insensitive to key model specifications and countries’ varying protection against unsafe drinking water. We suggest communicators and policymakers improve messaging about water safety and other environmental threats by explaining how they are impacted by worsening severe weather.