Sulfate Testing

Sulfate minerals can cause a build-up of scale in water pipes which may be associated with a bitter taste in drinking water. High sulfate levels in drinking water can have a laxative effect.  

According to the WHO the levels of sulfate commonly found in drinking water is not a concern for health, therefore there are no health-based guidelines for sulfate in water. However, they do state that below 250 mg/L sulfate is less likely to affect the taste of the water.  

The US EPA class sulfate as a secondary contaminant and specify a maximum level of 250 mg/L. This is based on aesthetic effects, including the taste and smell of the water, rather than health effects. To find out more about Secondary Drinking Water Standards click here.  

The FDA also give a secondary maximum contaminant level of 250 mg/L for sulfate, and the DWI also state a guideline value of 250 mg/L.  

To remove sulfate from water there are three main physical treatment technologies commonly used. These are reverse osmosis, distillation or ion exchange. Sulfate can also be removed using chemical treatment such as lime precipitation or biological treatment methods. 

Many wastewaters contain high concentrations of sulfate. This is common in wastewaters from mining or mineral processing industries. The wastewater may be subject to discharge limits of sulfate between 250 and 2000 mg/L and therefore it is often necessary to remove extra sulfate prior to discharge. 

As water moves through soil and rock formations that contain sulfate minerals some of the sulfate dissolves into water. Examples of minerals containing sulfate are magnesium sulfate (Epsom salt), sodium sulfate (Glauber’s salt) and calcium sulfate (gypsum).