evidence: Acidity in bottled drinking water not a cause for health concern, contrary to popular Facebook video claim [...] Imprecise: The reason why acidity in bottled drinking water would be bad for health is not explained in the video. [...] In truth, many liquids that we take in, such as fruit juices (e.g. orange, lemon, tomato), have an acidic pH – some are even much more acidic than those reported in the video – and yet fruit juices are generally considered to be healthy. Because pH levels are measured on a logarithmic scale, a difference of 1 unit corresponds to a factor of 10 (or one order of magnitude) in hydrogen ion concentration, so orange juice with its pH of 3 is ten thousand times more acidic than water with a neutral pH, and a hundred times more than water with a pH of 5. In other words, you would need to drink 15L (~4 gallons) of the more acidic bottled water shown in this video (pH=5) at a given time to achieve the same acidity as a glass of 0.15L of orange juice (pH=3).