How hard is the City of San Luis Obispo s water?
The phrase water hardness is a measure of calcium and magnesium salts dissolved in water. In the City of SLO, the water hardness is 200-370 mg/l (11.7 to 21.6 grains per gallon). The moderate hardness of the City s water does not pose a health problem. Hardness in water does tie up detergents and soap so that they will not lather. The harder the water, the more soap must be used to get things clean. Groundwater from the City s wells is generally harder than the surface water from the lakes.
