Regulations, Monitoring, and Recordkeeping
Rules, sampling, and documentation
The Safe Drinking Water Act and national primary drinking water regulations set the framework; the primacy agency (often the state) adopts and enforces rules. Know the difference between an MCL (maximum contaminant level), an MRDL (maximum residual disinfectant level), and a treatment technique (TT) - a TT is a required process when a safe level cannot be reliably measured. The Revised Total Coliform Rule uses sampling and assessment (Level 1 and Level 2) rather than a simple MCL, and the Consumer Confidence Report (CCR) must reach customers by July 1 each year.
Monitoring plans specify sites, frequency, and analytical methods. Representative sampling sites, proper bottles, holding times, and chain of custody matter; a bad sample can trigger unnecessary public notice. Public notification is tiered by risk: Tier 1 for immediate serious risk (such as an MCL violation with acute risk), Tier 2 for other violations, and Tier 3 for less urgent items. Recordkeeping includes operating logs, chemical usage, pump runtimes, valve and hydrant records, backflow tests, and sample results; retention periods vary by record type, so know the required schedule.
Traps: reporting an MCL where the rule is a treatment technique; missing the CCR deadline; sampling at a non-representative site; discarding records too early.
Rule of thumb: when a result is unusual, first verify sampling technique, site, and holding time before reporting - then follow the required notification timeline.