Frequent Questions

Should IDSE samples be collected during the warmest month or during the month of highest DBP levels?

IDSE samples should be collected in the month of peak historical TTHM/HAA5 formation. If the system does not have adequate historical data to determine this, the samples should be taken during the month of warmest water temperature.

For additional guidance on the Stage 2 Disinfectants and Disinfection Byproducts rule please visit

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