Americans have a lot of questions about their drinking water. How is it treated? What’s in it? Most importantly, is it safe? “I’ve even been out to eat where people overhear me talking about my work and come over to ask me a question about their tap water,” said Kimberly Parker, an environmental engineer who studies chemical contaminants in drinking water at Washington University in St Louis. Most Americans have access to municipal water, which “tends to be really well treated” and largely safe to drink, said Parker. Across the US, water is monitored for contamination via centralized infrastructure at federal and state levels. In Parker’s experience, “many environmental engineers choose not to use filtered water” because of their informed confidence in the safety of tap water, she said.