Industrial waste water, household waste water, runoff from a hazardous waste site or naturally decaying material can put sulfates into waterways rivers, lakes and streams. Wastes that contain sulfates seep through soil and contaminate groundwater. One national survey found that sulfates in drinking water supplies range from less than 1 ppm to over 700 ppm. The average level in the survey was 46 ppm. Sulfate levels in Wisconsin groundwater generally range from 15 to 60 ppm.
Sulfates are naturally present, at safe levels, in many foods.
Many sulfate salts can react in air to form dilute acid, which can irritate eyes. People who live near such industrial areas may notice irritating levels of sulfates in air. This is called a secondary standard because it's based on taste rather than health effects. Most people can taste or smell sulfates in their water at 300 ppm or higher. Some sensitive people can taste the salts at levels as low as 200 ppm.