Drinking Water Standard
Sulfates (SO4) are naturally occuring substances found in most waters. They're present in many disolved minerals, including barite, epsomite and gypsum. Sulfates and sulfuric acid products are used in the manufacture of fertilizers, chemicals, and in many other industries.
Large amounts of sulfate in drinking water can cause a laxative effect. According to the EPA:
Of particular concern are groups within the general population that may be at greater risk from the laxative effects of sulfate when they experience an abrupt change from drinking water with low sulfate concentrations to drinking water with high sulfate concentrations.
Bacteria which feed on sulfate are the main cause of hydrogen sulfide H2S .
Sulfate is easily removed by reverse osmosis (97 to 98%), and sulfates can also be reduced by a strong base anion exchanger.
(whole house & well units)