“Waters from snow and ice are all bad,” opined Hippocrates of Cos around 400 bc. “Once frozen, water never recovers its original nature, but the clear, light, sweet part is separated out and disappears.” Such melted waters, he declared, “are the worst for all purposes.”

Many medical experts disdain the widely circulated idea that adults need to drink eight glasses of water per day; most agree that solid foods alone provide enough hydration. Barbara Rolls, a nutrition researcher at Pennsylvania State University, was asked in 2001 about the origin of the spurious rule. “I can’t even tell you,” she said, “and I’ve written a book on water.”

In an experimental paper published in the International Journal of Nanotechnology in 2016, researchers reported discovering a phase of water that is not solid ice, liquid water, or vapor gas. The fourth state is found at around 50 degrees Celsius and behaves a bit like liquid crystal.

Analysis of lead pipe from the buried city of Pompeii revealed in 2017 that the Roman water supply may have had high levels of antimony, a toxic element likely used to increase the pipes’ strength. “It’s bigger than the diarrhea,” said an expert in archaeological chemistry about antimony’s possible effect on the population. “It’s the decline of the Roman Empire in 476.”