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GRAINS PER GALLON (GPG) Definition & Legal Meaning

Definition & Citations:

Water hardness as a measured unit. 1 grain (64.8 milligrams) of calcium carbonate dissolved in 1 US gallon of water equals one GPG. It figures out to be 14.3 parts per million (PPM) or 1 part in 70,000 parts of water. Known also as Clark degree. Also refer to hard water.


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