The Safe Drinking Water Act (SDWA), as amended in 1996, requires the Environmental Protection Agency (EPA) to review and revise, if appropriate, existing National Primary Drinking Water Regulations (NPDWRs). Review involves consideration of five key elements, as appropriate: health effects, analytical and treatment feasibility, implementation-related issues, occurrence and exposure, and economic impact. This report addresses the analytical feasibility aspect of the review which has been based on the laboratories' analytical performance data generated as part of the EPA's certification program for drinking water laboratories. This analytical feasibility assessment is based jointly on the recent analytical performance data collected during the second six year review as well as on earlier data collected during the first six year review. Efforts are also made to determine if the analytical performance assessments based on the laboratory data are supported by the approval of improved methods or revision of existing methods since the last review. The goal is to create a comprehensive document that addresses all regulated chemical analytes for which data are available.