Frequent Questions

Our water system is subject to the Stage 1 Disinfectants and Disinfection Byproducts (DBP) Rule. What requirements must we meet to qualify for reduced monitoring for disinfectant byproduct precursors (DBPP)?

Subpart H systems with an average treated water total organic carbon (TOC) of less than 2.0 mg/L for two consecutive years, or less than 1.0 mg/L for one year, may reduce monitoring for both TOC and alkalinity to one paired sample and one source water alkalinity sample per plant per quarter (40 CFR 141.132(d)(2)). The system must revert to routine monitoring in the month following the quarter when the annual average treated water TOC is greater than or equal to 2.0 mg/L.
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