Water quality criteria pollutants are a list of substances that are deemed unhealthy for public consumption as drinking water. These standards vary world-wide; what is applicable in the European countries is not the same standard as the Safe Water Act that dictates United States water quality standards. There are elemental concerns of pollutants, such as lead, cadmium, fluorine, chlorine, sodium, calcium, magnesium, and mercury. There are microorganism concerns, bacteria that could potentially be life-threatening and have caused epidemic outbreaks historically. Examples of those would be typhoid, e. coli, and ebola. There are pollutants from the environment that occur naturally, such as raw sewage from city sewer systems, that must filter out solid trash and sewage, then treat the water by killing the microorganisms that feed on such organic waste. Any and all these pollutants can have direct health ramifications and should be closely and carefully monitored.