The SDWA requires the EPA Administrator to promulgate National Primary Drinking Water Regulations (NPDWRs) that specify maximum contaminant levels (MCLs) or treatment techniques for listed drinking water contaminants (section 1412). In addition, section 1445(a) of SDWA authorizes the Administrator to establish regulations for monitoring to assist in determining whether persons are acting in compliance with the requirements of SDWA. EPA's approval of analytical test procedures is authorized under these sections of SDWA, as well as the general rulemaking authority in SDWA section 1450(a).
Under the ATP program, an organization may submit an application for approval of a modified version of an approved method or for approval of a new method to be used as an alternate to an approved method. The submitting organization is responsible for validating the new or modified method. The Agency reviews the ATP validation package and, if required, promulgates successful applications in the CFR. Rulemaking is required when a new or revised method is added to the list of approved methods in the CFR. The ATP and rulemaking processes make heavy demands on stakeholder, contractor, EPA, and Federal Register resources. These processes can require several months to approve a minor method modification and a year or more to promulgate a major modification or a new technology. Because advances in analytical technology continue to outpace the capacity of OW’s method approval program, the program has been under-utilized and slow to respond to emerging technologies. This protocol is intended to specify a more rapid and less resource intensive process for approval of new technologies.
The following webpage has documentation highlighting the approval process : http://water.epa.gov/scitech/methods/cwa/atp/questions.cfm#askEPA