Most acidic water

Water running through the Richmond Mine at Iron Mountain, California, US was sampled in 1990 and 1991 and found to have a pH value of       -3.6.  The source of the acid in the water was hot acid solutions dripping off coloured stalactites in an abandoned copper and zinc mine at Iron Mountain, California. pH values range from 0 to 14 with 7 being neutral.  Water has a pH of 7 for example.  The lower the number the higher the acid level of any given substance. The study was made by Darrell Kirk Nordstrom and Charles Alpers of US Geological Survey and published in the American Chemical Society Journal.