Hardness is a measure of naturally occurring calcium and magnesium minerals dissolved in water, the higher the mineral content, the harder the water. The following table classifies hardness by category based on mineral content in milligrams per liter. City of Longview groundwater hardness ranges from 69 to 91 milligrams per liter and is considered to be “moderate”. According to the U.S. Geologic Survey, more than 85% of the United States has hard water.
|Classification||Hardness (milligrams per liter)|
0 to 60
61 to 120
121 to 180
Greater than 180