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The Drinking Water Method Update Rule updates the approved analytical methods for regulatory compliance monitoring as required in the National Primary Drinking Water Regulations (NPDWR), under the Code of Federal Regulations (CFR) at 40 CFR part 141. The modification goals include: 1) Transferring methods approved under the Drinking Water Expedited Method Approval process from 40 CFR part 141, appendix A to subpart C, to the appropriate regulatory method tables in the regulation; 2) Removing methods that are obsolete or do not meet the technological or quality standards of more recent compliance monitoring analytical methodology; because newer methods use better technology and are more rugged due to the inclusion of quality control criteria; and 3) Clarifying or correcting language and tables in 40 CFR part 141 that are associated with drinking water analytical methodology or the analysis of drinking water contaminants and water quality parameters, which allows drinking water utilities and laboratories to have a clearer understanding of the compliance monitoring analytical requirements described in the NPDWRs. Pre-proposal stakeholder engagement will occur at national conferences such as the Environmental Measurement Symposium (EMS). This action is not anticipated to have substantive adverse reaction or comments.