Coliform Bacteria Level 1 Assessment

PWS self-assessment to review response to a coliform bacteria MCL violation


The Environmental Protection Agency (EPA) published the Revised Total Coliform Rule (RTCR) in the Federal Register on February 13, 2013 and minor corrections on February 26, 2014. The RTCR is a revision of the 1989 Total Coliform Rule (TCR) and is intended to improve public health protection. Minor corrections to the final RTCR became effective on April 28, 2014. No comments were received on the Direct Final Rule published on February 26, 2014. The corrections therefore became effective without further notice. All public water systems (PWSs), must comply with the RTCR as of April 1, 2016.

Under the RTCR, a PWS that is vulnerable to microbial contamination is required to conduct an assessment and corrective action of the system to identify and correct any sanitary defects in the distribution system or treatment processes. Under the RTCR, EPA uses total coliform (TC) as indicators of the microbial integrity of the distribution system, and E. coli as an indicator of the presence of fecal contamination.

The purpose of performing assessments is to enhance public health protection by identifying the presence of "sanitary defects" (defects that could provide a pathway of entry for microbial contamination into the distribution system or that are indicative of a failure or imminent failure in a barrier that is already in place). Sampling results can trigger an assessment designed to take a closer look at the system and to identify whether one or more sanitary defects are present.

Assessment and Corrective Action

The PWS should conduct a Level 1 assessment if it exceeds any of the following triggers:

  • A PWS collecting fewer than 40 samples per month has 2 or more TC+ routine/repeat samples in the same month.
  • A PWS collecting at least 40 samples per month has greater than 5.0 percent of the routine/repeat samples in the same month that are TC+.
  • A PWS fails to take every required repeat sample after any single TC+ sample.

Level 1 Assessment

The Level 1 assessment consists of an examination of the system's source water, treatment, distribution system, and relevant operational practices. While the Level 1 assessment is intended to be a relatively simple assessment, it should be conducted thoroughly enough to capture the possibility that there may be multiple sanitary defects. Systems should complete the entire assessment form, even if they believe they understand the apparent cause, to ensure they have a holistic picture of the overall integrity of their system and do not inadvertently overlook a sanitary defect. Ideally, a well-performed Level 1 assessment will prevent most systems from developing conditions that lead to a Level 2 assessment.

The Level 1 Assessment is a self-assessment. This assessment is intended for the PWS to review general water system infrastructure, operating and sampling protocols in response to a total coliform bacteria MCL violation, and should be completed by a knowledgeable representative of the water system. A Level 1 assessment should be conducted or managed by a responsible party of the PWS. This should be someone familiar enough with the system to answer the questions in the Level 1 Assessment form or to gather correct information from others who work for the system. Having the PWS responsible for having the assessment conducted also serves to strengthen the PWS's capacity to ensure that barriers to contamination are in place and are effective in the future.


Public Water Systems conducting a Level 1 Assessment must fully complete the Coliform Bacteria Level 1 Assessment Form.  The PWS will provide MassDEP with a completed Level 1 Assessment form within 30 days after determination of exceeding a Level 1 Assessment trigger; the Level 1 Assessment trigger is a Total Coliform Maximum Contaminant Level (TCR MCL) violation. In an effort to ensure that the certified operator is aware of the violation and participates in the Level 1 Assessment, both the certified operator and the responsible party filling out the Level 1 Assessment form (if different than the certified operator) must sign the document.

Since the form cannot cover all possible situations or distribution system configurations Assessors should use professional judgment in the application of the forms to their system and provide additional information to support conclusions, if warranted.

The Level 1 Assessment form may be used in lieu of ATTACHMENT H COLIFORM VIOLATION EVALUATION SURVEY which is part of Guidelines and Policies for Public Water Systems Appendix O, HANDBOOK FOR WATER SUPPLY EMERGENCIES.

To complete this form electronically, click on the gray boxes and type in your responses. For printed forms, write in your responses. All forms must be completely filled out and returned to the MassDEP office where the system is located.

If you have any questions on Level 1 assessment requirements please contact the Drinking Water Program.

If you are a small system serving less than 10,000 users and you need technical assistance, contact Dave Kaczenski of the Massachusetts Rural Water Association at 866-451-8099 or email, James Starbard of RCAP Solutions at 978-502-0227 or, or contact the appropriate MassDEP staff:

CERO: Paula Caron, 508-767-2719
NERO: Jim Persky, 978-694-3227 or Zach Peters, 978-694-3247
SERO: Karen Dube, 508-946-2720
WERO: Susan Steenstrup, 413-755-2264
Boston: Mike Maynard, 508-767-2735

Additional Resources

Contact   for Coliform Bacteria Level 1 Assessment

Help Us Improve  with your feedback

Please do not include personal or contact information.