Water Quality Standards

Sulfates occur naturally in numerous minerals and are used commercially, principally in the chemical industry. They are discharged into water in industrial wastes and through atmospheric deposition; however, the highest levels usually occur in ground water and are from natural sources. In general, food is the principal source of exposure to sulfate, although intake from drinking-water can exceed that from food in areas with high concentrations. The contribution of air to total intake is negligible.

Sulfate is one of the least toxic anions; however, catharsis, dehydration, and gastrointestinal irritation have been observed at high concentrations. Magnesium sulfate, or Epsom salts, has been used as a cathartic for many years. 

No health-based guideline is proposed for sulfate. However, because of the gastrointestinal effects resulting from ingestion of drinking-water containing high sulfate levels, it is recommended that health authorities be notified of sources of drinking-water that contain sulfate concentrations in excess of 500 mg/litre. The presence of sulfate in drinking-water may also cause noticeable taste (see Acceptability aspects) and may contribute to the corrosion of distribution systems.