EPA

The main vehicle by which the EPA regulates drinking water is through the Safe Water Drinking Act (SDWA) and its amendments. The SDWAwas established to protect the quality of drinking water in the US. The law focuses on all waters actually or potentially designed for drinking use, whether from aboveground or underground sources. Regulations do not apply to private wells serving fewer than 25 individuals with fewer than 15 service connections. The total number of regulated public water systems is greater than 170,000.

The basic approach of the SDWA is to identify and regulate potentially hazardous water contaminants. These contaminants include naturally occurring substances, animal wastes, pesticides, wastes injected underground, byproducts of water disinfection, chemicals spilled or improperly exposed, and contaminants from improperly maintained distribution systems. Regulations target both water treatment and protection of water sources.

The NationalPrimary Drinking Water Standards identify drinking water contaminants that may adversely affect public health. For the identified primary contaminants, the EPA identifies a maximum contaminant level, the maximum permissible level of a contaminantin drinking water. These levels are enforceable standards, and are selected as feasible targets for best available technology, taking cost into consideration. Contaminants are classified into the following groups: microorganisms, disinfectants, disinfection byproducts, inorganic chemicals, organic chemicals, and radionuclides.

There is another class of contaminants regulated under the National Secondary Drinking Water Standards. These are non-enforceable guidelines regulating contaminants that are not considered a health threat, but pose cosmetic or aesthetic effects, such as odor, taste, and color of the water, or discoloration and staining of teeth, laundry, etc. There are 15 identified secondary contaminants for which the EPA has identified secondary maximum contaminant levels. While not enforceable by the EPA, these standards can be enforced by individual states, and Texas has done so.

For the most part, direct oversight of water systems is conducted by state drinking water programs. All states and territories except Wyoming and DC have received “primacy”, the right to implement theSDWA within their jurisdictions. As part of primacy, states adapt standards at least as stringent as the EPA’s, and make sure water systems meet these standards.