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Monitoring Unregulated Drinking Water Contaminants

Laboratory Approval Program for the Fourth Unregulated Contaminant Monitoring Rule (UCMR 4)

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Basic information about the UCMR 4 laboratory approval program

All laboratories conducting analyses for the Unregulated Contaminant Monitoring Rule (UCMR) must be approved by EPA.

The UCMR laboratory approval program currently only applies to laboratories analyzing samples for the fourth Unregulated Contaminant Monitoring Rule (UCMR 4). Laboratories that successfully completed a registration and application process received approval from EPA.

  • The UCMR 4 list of approved laboratories was finalized in early 2018 and updated as needed. Applications are no longer being accepted.

The laboratory approval program was designed to assess whether laboratories meet the required criteria described under UCMR 4 for:

  • Equipment
  • Laboratory performance
  • Data reporting

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Step-by-step laboratory approval process

Applicants already certified for UCMR 4 methods by their state or EPA Region to conduct drinking water analyses were also required to complete the UCMR 4 approval steps, including analyzing the UCMR 4 proficiency test (PT) sample. The steps for the laboratory approval process were:

1. Request to participate
Laboratories interested in the UCMR 4 laboratory approval program first emailed EPA at to request registration materials.

2. Registration
Laboratory applicants provided registration information that included: laboratory name, mailing address, shipping address, contact name, phone number, email address and a list of the UCMR 4 methods, for which the laboratory was seeking approval. This registration step provided EPA with the necessary contact information, and ensured that each laboratory received a customized application package.

Note: Laboratories (including PWS laboratories) that wished to exclusively analyze total organic carbon (TOC) and/or bromide were not required to undergo all of the steps for UCMR 4 laboratory approval. Rather, under a similar process, they emailed the to register for the Laboratory Approval Program. Next, the PWS laboratory completed the registration and submited documentation that they are authorized by their primacy state to analyze TOC and/or bromide compliance monitoring samples under the Stage 2 Disinfectants and Disinfection Byproduct Rule (DBPR).

3. Application package
Laboratories completed and returned a customized application package that included the following: initial demonstration of capability (IDC) data, including precision, accuracy and results of MRL studies; information regarding analytical equipment and other materials; proof of current drinking water laboratory certification (for select compliance monitoring methods); and, example chromatograms for each method under review.

As a condition of receiving and maintaining approval, the laboratory was required to confirm that it will post UCMR 4 monitoring results and quality control data that meet method criteria (on behalf of its PWS clients) to EPA's UCMR electronic data reporting system, the Safe Drinking Water Accession and Review System (SDWARS).

4. EPA’s review of application package
EPA reviewed the application packages and, when necessary, requested follow-up information. Laboratories that successfully completed the application process became eligible to participate in the UCMR 4 PT program.

5. Proficiency testing
A PT sample is a prepared synthetic sample containing a concentration of an analyte or mixture of analytes that is known to EPA, but unknown to the laboratory. To be approved, a laboratory was required to meet specific acceptance criteria for the analysis of a UCMR 4 PT sample(s) for each UCMR analyte in each method, for which the laboratory sought approval. EPA offered five opportunities for a laboratory to successfully analyze UCMR 4 PT samples.

EPA will not conduct additional PT studies after the start of monitoring; however, laboratory audits will likely be ongoing throughout UCMR 4 implementation. Continued laboratory approval is contingent on successful completion of the audit process and satisfactorily meeting all the other stated conditions.

6. Written EPA approval
After laboratories successfully completed steps 1 through 5, EPA sent each laboratory a letter listing the methods, for which approval was granted.

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Maintaining laboratory approval

Approved laboratories must adhere to the quality assurance and quality control procedures and criteria outlined in the method(s) and rule language to maintain their approval status.

Laboratories are also required to post sample data and required quality control data electronically via the Safe Drinking Water Accession and Review System (SDWARS) within 120 days of sample collection date. Failure to post data using SDWARS will generally result in EPA revoking the laboratory's approval status.

Once a laboratory is disapproved, EPA does not anticipate any opportunity for reinstatement during the UCMR 4 monitoring period. Approved laboratories are subject to on-site laboratory and/or off-site (paper) audits.

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