Action Level (AL)
An action level is a concentration of a contaminant that, when exceeded at the 90th percentile of tap water samples, requires a water system to take specific corrective steps — not because it is the maximum allowed concentration, but because it is the threshold that triggers required action.
Where you'll see it on a CCR
Your Consumer Confidence Report must disclose whether the system exceeded the action level for lead or copper during the monitoring period. You'll find this in the lead and copper section, which reports the 90th-percentile tap sample result alongside the applicable AL. Systems that exceeded the AL must include additional language describing corrective steps underway. See the CCR glossary for related terms.
How an action-level exceedance differs from an MCL violation
This is the distinction most people miss when reading a CCR.
A maximum contaminant level (MCL) is the highest concentration of a substance legally permitted in water delivered to customers. Exceeding an MCL is a direct violation of a legal limit.
An action level works differently. Lead and copper are regulated as treatment techniques, not as MCLs. The AL is not a cap — it is a statistical trigger. When the 90th-percentile tap sample result exceeds the AL, the system must take prescribed steps: optimize corrosion control, review source water treatment, conduct public education, and — for lead — replace lead service lines. Codified at 40 CFR § 141.80(c).
An exceedance means obligations have activated, not that a concentration limit was broken.
Lead and copper action levels under LCR/LCRI
The current action levels, and the change coming in 2027:
| Contaminant | Current AL (LCR, 1991) | AL under LCRI (effective Nov 1, 2027) | |---|---|---| | Lead | 15 µg/L (0.015 mg/L) | 10 µg/L (0.010 mg/L) | | Copper | 1.3 mg/L | 1.3 mg/L (unchanged) |
The Lead and Copper Rule Improvements (LCRI), finalized October 2024 and effective November 1, 2027, lower the lead action level from 15 to 10 µg/L. A system compliant at 12 µg/L today will exceed the AL after that date. Systems should check their current 90th-percentile results against the incoming threshold now.
The LCRI also changes sampling at lead service line sites. Systems must collect paired first-liter and fifth-liter samples and use the higher of the two values when computing the 90th-percentile result. This paired protocol is designed to capture lead at the service line more reliably than prior single-draw methods.
For compliance timelines, see LCRI 2027 and the lead contaminant page.
Related terms
- Treatment technique — the regulatory mechanism under which lead and copper ALs operate; explains why an AL exceedance is not an MCL violation
- Lead service line replacement — the primary remediation obligation triggered when the lead AL is exceeded under LCRI
- LCRI 2027 — full compliance timeline and sampling protocol changes
Citations
- 40 CFR § 141.80(c) — Action level definition and treatment technique trigger: law.cornell.edu/cfr/text/40/141.80
- Lead AL under LCR (1991): 15 µg/L (0.015 mg/L)
- Lead AL under LCRI (effective Nov 1, 2027): 10 µg/L (0.010 mg/L) — 89 FR 86416, document ID 2024-23549
- Copper AL: 1.3 mg/L, unchanged across LCR, LCRR, and LCRI
- LCRI paired sampling protocol (1st- and 5th-liter): 89 FR 86416
Last reviewed: 2026-05-03. Regulatory facts verified against primary CFR text and Federal Register notices.