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Stage 2 Disinfectants & Disinfection Byproducts Rule

The Stage 2 Disinfectants and Disinfection Byproducts Rule was published in the PA Bulletin on December 26, 2009.

The US Environmental Protection Agency published Stage 2 to supplement existing regulations by requiring drinking water suppliers to meet disinfection byproduct maximum contaminant levels at each monitoring site in the distribution system. The rule seeks to better identify monitoring sites where customers are exposed to high levels of disinfection byproducts. This regulation will reduce byproduct exposure, provide more equitable health protection, and result in lower cancer and reproductive and developmental risks.

Stage 2 D/DBP Job Aids and Training Material

D/DBP Rules Monitoring and Reporting Requirements Summary (PDF)
This job aid summarizes the routine and reduced monitoring requirements for all system types.

Monitoring Plan for the Disinfectants-Disinfection Byproducts Rules Form and Instructions
These two eLibrary files contain a Stage 2 D/DBP monitoring plan template and instructions for completing this template. The instructions provide the regulatory requirements and deadlines for completing the monitoring plan.

Stage 2 DBP Rule Review Water Supplier Training Course Workbook (PDF) – 2021
This updated 2021 workbook reviews how to comply with the rule, including an exploration of the unique Stage 2 DBP rule requirements of performing MCL compliance and Operational Evaluations. It includes a review of best management practices to maintain simultaneous compliance with the Disinfection Requirements Rule and Stage 2.

Stage 2 DBP Rule Water Supplier Training Course Workbook (PDF)
If you missed the classes during the summer of 2013, this is the workbook to guide you through complying with the rule.

OEL Requirements

All systems subject to the Stage 2 rule that are required to collect quarterly compliance samples must comply with the operational evaluation requirements of the rule. After each quarter, the Operational Evaluation Level (OEL) must be calculated for both TTHM and HAA5 to determine if there is an OEL exceedance. If an OEL exceedance occurs, the system must conduct on operational evaluation and submit a report to DEP within 90 days of being notified of the sample result that caused the exceedance. DEP has developed an Operational Evaluation Level Exceedance Notification Form to assist water systems in reporting the required information to DEP.

EPA’s OEL Guidance Manual (PDF) can be found under Stage 2 D/DBP External Web Links below. Following are the EPA checklists and forms that a system may use for conducting the operational evaluation and submitting the report to DEP.

Water Quality Assessment Software (WQAS)

The WQAS is designed to assist all public drinking water systems required to monitor for DBPs under the Stage 2 DBP Rule. Compliance with the Stage 2 DBPR is calculated by the Pa. DEP based on the data submitted by the certified laboratory conducting the analysis. However, the WQAS does include a calculation for the Operation Evaluation Level (OEL), which is required to be calculated by public water systems monitoring quarterly, in accordance with the PA Safe Drinking Water Regulations subparagraph §109.701(g)(2)(iii). Be sure to follow the software instructions closely in the MS Word file.

Stage 2 D/DBP External Web Links

EPA's Stage 2 D/DBPR Information
This link will take you to EPA's website on the Stage 2 Disinfectants and Disinfection Byproducts Rule. You can view or download technical guidance manuals, obtain fact sheets, and see the federal version of the rule.

EPA has created guidance for Operational Evaluation Levels:
EPA OEL Guidance Manual (PDF)

Additional information can be found on EPA's Stage 1 and Stage 2 D/DBP Compliance Help for Systems page:
EPA's Stage 1 and Stage 2 Compliance Help for Community Water System Owners and Operators.