EPA's regulations prohibit any underground injection that "allows the movement of fluid containing any contaminant into underground sources of drinking water, if the presence of that contaminant may cause a violation of any primary drinking water regulation .

A regulatory determination is a formal decision on whether EPA should initiate a rulemaking process to develop a national primary drinking water regulation (NPDWR) for a specific contaminant.

However, this action initiates a process to develop and establish a national primary drinking water regulation (NPDWR).

This entails providing air carriers with a feasible way to comply with the Safe Drinking Water Act (SDWA) and the national primary drinking water regulations (NPDWRs).

An injection activity has the potential to endanger if the presence of that contaminant may cause a violation of any primary drinking water regulation or may adversely affect human health.

The Safe Drinking Water Act requires EPA to periodically review the national primary drinking water regulation for each contaminant and revise the regulation, if appropriate.

The Administrator shall, not less often than every 6 years, review and revise, as appropriate, each national primary drinking water regulation promulgated under this title.

Any revision of a national primary drinking water regulation shall be promulgated in accordance with this section, except that each revision shall maintain, or provide for greater, protection of the health of persons.

National primary drinking water regulations set the maximum contaminant level (MCL) of 0.1 mg/L for total chromium, which includes chromium-6 (hexavalent chromium), and requires community and non-transient non-community water systems to test for chromium at the entry point to the distribution system.

An alphabetical listing with links to fact sheets on the primary drinking water regulations.