/oss/taxonomy/term/2227/all en /oss/article/controversial-science-health-quackery/should-one-worry-about-reboiling-water-coffee-or-tea <p>An article is circulating on the internet about the dangers of reboiling water and concentrating dissolved chemicals. It amounts to baseless fear-mongering. Lets consider fluoride as an example. Suppose you put a liter of water containing 1 ppm fluoride in a kettle and boil it. You then take 200 mL to make a cup of coffee or tea. That means you will ingest 0.2 mg of fluoride. If you now let the water keep boiling until 100 mL evaporates...which would take a long time...and you take 200 mL from the remaining water to make your next cup of coffee, you will be ingesting 0.22 mg of fluoride.</p> Tue, 30 Jun 2015 08:29:31 +0000 Joe Schwarcz 2269 at /oss