Drinking Water Priority Rulemaking: Radon
Statutory Requirements and Timetable
The 1996 Amendments to SDWA added new radon requirements (section 1412 (b) (13). EPA
Withdraw the 1991 proposed radon regulation;
Arrange for the National Academy of Sciences (NAS) to conduct a risk assessment for
radon in drinking water and an assessment of the health risk reduction benefits associated with various mitigation methods of reducing radon in indoor air;
Publish a radon health risk reduction and cost analysis for possible radon MCLs for
public comment, by February 1999;
Propose MCL Goal and National Primary Drinking Water Standard for radon by
Publish MCL Goal and Final MCL for radon, by August, 2000.
If the MCL is "more stringent than necessary to reduce the contribution to radon in indoor air from drinking water to a concentration that is equivalent to the
national average concentration of radon in outdoor air," EPA must establish an
"alternative MCL" (AMCL). The level of the AMCL is linked to average outdoor
- If an alternative MCL is established, EPA must publish guidelines for State
multimedia radon mitigation programs.
- States may develop (and submit to EPA for approval) a multimedia mitigation
program to mitigate radon levels in indoor air.
- EPA shall approve State multimedia mitigation programs if they are expected to
achieve equivalent or greater health risk reduction benefits than compliance with
- If EPA approves a State multimedia mitigation program, public water supply systems within the State may comply with the alternative MCL.
- EPA shall evaluate multimedia mitigation programs every 5 years.
More information about Radon in drinking water.