Water Reuse

Federally Regulated Drinking Water Contaminants

Microbial Contaminants
When concerned primarily with contaminants that may be found in wastewater, it is appropriate to focus on microbial contaminants. While it is true that wastewater may contain other contaminants of concern, the primary public health risk would seem to come from microbes. Under SDWA, the US EPA has regulations to address Cryptosporidium, Giardia lamblia, Legionella, Coliforms, and Viruses. With the exception of Coliforms, all of these microbes are addressed using the Treatment Technique approach. It should also be noted that while these are the only microbes specifically mentioned in EPA regulations, they are by no means the only possible microbes to be found in drinking water. For example, EPA's Contaminant Candidate List (which lists contaminants that EPA is considering regulating) contains eight other microbes.

Disinfectants and Disinfection Byproducts
These contaminants are found in drinking water as a result of treatment used to disinfect the water. While disinfectants are required in many instances to kill or inactivate pathogens, it is important to realize that there are some unintended consequences of this treatment. First of all, the disinfectants themselves, such as Chlorine or Chloramine, may have adverse health effects at high enough doses. In addition, when disinfectants react with organic materials found in the water, dangerous byproducts such as trihalomethanes can form. Therefore, drinking water providers must balance the risks of the disinfection process against the risks of the pathogens.

Inorganic Contaminants
Many inorganic contaminants are regulated under SDWA. These include primarily metals, but also other substances such as asbestos and nitrate.

Organic contaminants
Many organic contaminants are also regulated. The substances in this category are mostly made up of pesticides and wastes from various industrial processes.

Radionuclides
Some radionuclides are regulated as well. This includes Radium and Uranium, but there are also rules regarding alpha paticles and beta particles.


Sources:
Federal Register: February 24, 2005 (Volume 70, Number 36) (CCL2 information)
http://epa.gov/safewater/contaminants/index.html