Utilities > Water > Water Treatment > Water Quality

Water Quality

Hardness
How hard is the City of San Luis Obispo's water?  In the City, the water hardness is 200 to 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 clean.  Soft water, on the other hand, can be more corrosive to plumbing. Groundwater from City wells is generally "harder" than the surface water from the lakes.

Fluoride
Does the City add fluoride to the water supplied to residents? Yes. 

The City has been fluoridating our water since August 3, 1954, following an advisory vote of the citizens in the City. Fluoride has been found to be an effective tool in preventing dental problems when used in optimal concentrations.

Click here view our annual Water Quality/Consumer Confidence Reports: