January 22, 2001: Final Rule for Arsenic in Drinking Water.“Today’s final rule revises the current Maximum Contaminant Level (MCL) from 50 µg/L to 10 µg/L and sets a Maximum Contaminant Level Goal (MCLG) of zero for arsenic in drinking water. In addition, this final rule also clarifies how compliance is demonstrated for many inorganic and organic contaminants in drinking water…. Both community water systems (CWSs) and non-transient, non-community water systems (NTNCWSs) will be required to reduce the arsenic concentration in their drinking water systems to 10 µg/L…. All CWSs and all NTNCWSs that exceed the MCL of 10 µg/L will be required to come into compliance 5 years after the publication of the final rule. Beginning with reports that are due by July 1, 2002, all CWSs will begin providing health information and arsenic concentrations in their annual consumer confidence report (CCR) for water that exceeds ½ the new MCL….
In the 1996 amendments to the Safe Drinking Water Act (SDWA), Congress directed EPA to propose a new arsenic regulation by January 1, 2000 and to issue the final rule by January 1, 2001 (Congress subsequently extended the final rule date to June 22, 2001). EPA published the proposed rule for arsenic on June 22, 2000. The rule proposed an MCL of 5 µg/L for arsenic and EPA took comment on regulatory options of 3 µg/L (the feasible level), 10 µg/L and 20 µg/L. The 1996 amendments to SDWA added discretionary authority for the EPA Administrator to adjust the maximum contaminant level (MCL) if the benefits would not justify the costs (§1412(b)(6)). Today’s rule is important because it is the second drinking water regulation in which EPA will use the discretionary authority under §1412(b)(6) of SWDA. After careful consideration of the benefits and the costs, EPA has decided to set the drinking water standard for arsenic higher than the technically feasible level of 3 µg/L because EPA believes that the costs would not justify the benefits at this level. EPA believes that the final MCL of 10 µg/L maximizes health risk reduction at a cost justified by the benefits.”
Commentary/Update: In January 2019, New Hampshire adopted an MCL for arsenic of 5 ppb.