Sulfate is present at widely varying concentrations in natural waters.  The USEPA has established a Secondary Drinking Water Standard of 250 mg/L for sulfate in potable water, as higher concentrations affect odor and taste.  Sulfate levels are also measured in the beverage industry due to their effect on odor and taste.  Sulfate levels must be monitored in cooling water and ion exchange systems in order to prevent calcium sulfate scale formation.

The sulfate Vacu-vials^® test method employs the turbidimetric method.  Sulfate ion reacts with  barium chloride in acidic solution to form a suspension of barium sulfate crystals of uniform size.  The resulting turbidity is proportional to the sulfate concentration of the sample.  Results are expressed as ppm (mg/L) SO₄.