Water Hardness test paper is packed with two rolls of test paper and two specially calibrated color charts. One roll measures between 0-20 grains per gallon of calcium carbonate. The second roll measures from 10-50 grains per gallon. The color chart has color matches at 0-5-10-20 grains per gallon. A reading of 5 grains per gallon indicates moderately hard water. The second roll of test paper has color chart matches 10-20-30-50 grains per gallon and is used for testing known hard water sources.