Fact Sheet: Sulfate


Brief Overview:
Contaminant: Sulfate
Category: Inorganic
MCL: 250 mg/L MCL, Secondary Drinking Water Standard
Source: Natural occurring, Commercial use
Effect: Short and Long-term Health Effects Test
Followup: Test for Sulfate and Total Dissolved Solids
Treatment: Reverse osmosis, distillation, or ion exchange

Sulfates are naturally occurring substances that are found in minerals, soil, and rocks. They are
present in ambient air, groundwater, plants, and food. The principal commercial use of sulfate is in the chemical
industry. Sulfates are discharged into water in industrial wastes and through atmospheric deposition. Sulfate
concentration in seawater is about 2,700 milligrams per liter Sulfate — February 2003 2 (mg/L). It ranges from
3 to 30 mg/L in most freshwater supplies, although much higher concentrations (1000 mg/L) are found in some
geographic locations. In the United States, the median concentration for a 20-State cross-section was 24 mg/L;
the 99th percentile value was 560 mg/L. In general, food is the principal source of exposure. However, in areas
with high sulfate concentrations, exposure from water can exceed that from food.

Acute exposures to sulfate exert a laxative effect (loose stool) and sometimes diarrhea (unusually
frequent or unusually liquid bowel movements) following acute exposures to high concentrations. However,
these effects are not observed for longer term exposures. This may be because of acclimation to sulfate over
time. In the case of sulfate, adults appear to adapt within 1 or 2 weeks and are no longer affected by the
sulfate in their drinking water supply. Infants, however, may be more sensitive.

Treat and re-test for total dissolved solids and sulfate

reverse osmosis, distillation, or ion exchange