A method for reporting the concentration of an ion or substance in a water.

          The following conversions apply for dilute waters with a specific gravity of 1.0: One ppm is equal to one mg/L. One Grain per U.S. Gallon is equal to 17.1 ppm. One Pound per 1,000 U.S. Gallons is equal to 120 ppm. A one per cent solution is equal to 10,000 ppm. One ppm is equal to 1,000 ppb.