It is also required to establish acceptable limits of these substances. Once again, the EPA does not require water companies to take corrective action unless specific pollutants exceed certain levels. While levels for many substances have been set, there are no limits, or the limits are being re-evaluated for others. Two that the EPA are looking at now are sulphate and arsenic both being naturally occurring substances. In recent years, the EPA has recognized that there are possible health concerns concerning sulfate in drinking water following reports of people contracting diarrhea after ingesting it.
Some people seem to be more affected than others.
EPA has been looking at this issue since the late 1990s. So has the Centers For Disease Control. While that is a small percentage, it can translate into a lot of real people. Thus, the EPA may provide us with a new acceptable level shortly. Arsenic is clearly potentially harmful if too much is consumed.