This is the true story of a man in Taiwan who used the same metal thermal mug every single day for a decade—for tea, coffee, juices, you name it. He thought he was being frugal.

What he didn’t know was that every sip came with a little dose of heavy metals. Over time, the inside of his mug started to rust. But he kept using it. Never deep-cleaned it. Never replaced it. Eventually, he began to feel unwell. By the time he saw a doctor, the diagnosis was chilling: lead poisoning—likely from long-term exposure to metal leaching into hot, acidic drinks. A year later, he died from complications related to pneumonia.

Experts warn: some old thermoses—especially if they’re not food-grade stainless steel—can slowly release toxic substances when exposed to heat or acid. Coffee, tea, fruit juice, even milk or herbal drinks can react with the metal. And the longer you use the same bottle without checking, the greater the risk. So if your bottle has rust spots, weird smells, or you’ve been using it since college… it’s probably time to say goodbye.

Staying eco-conscious is great—but not at the cost of your health. Doctors recommend switching bottles every 1–2 years, choosing food-safe materials like 304 stainless steel, ceramic, or glass, and avoiding acidic drinks in metal containers. Oh—and cleaning with baking soda or vinegar? That’s not just a grandma thing. It’s science. Your cup should hydrate you—not harm you. So before your next sip, maybe… check your thermos.