Regulated Contaminants in Your CCR

Every Consumer Confidence Report must list the contaminants your system detected or monitored for, paired with the Maximum Contaminant Level (MCL) for each one and any health-effects language required by federal rule. EPA sets the list and the language; your primacy agency may add to it.

What makes a contaminant "regulated"

A contaminant is regulated when EPA has set an enforceable limit — an MCL, a Maximum Residual Disinfectant Level (MRDL), or a Treatment Technique (TT) — under the Safe Drinking Water Act. The CCR rule at 40 CFR §§ 141.151–141.156 requires systems to report on every regulated contaminant that was detected during the monitoring period, plus any violations. For some contaminants, federal rule also mandates specific health-effects boilerplate regardless of whether an MCL was exceeded — the language must appear word-for-word (40 CFR § 141.154).

The pages below are organized by category. Each covers what the contaminant is, what the current limit is, what your CCR must say about it, and what recent regulatory changes (if any) affect your next report.

Inorganic contaminants

Lead Lead has no safe level in drinking water — its MCLG is zero (40 CFR § 141.51). The action level drops from 15 µg/L to 10 µg/L on November 1, 2027, when the Lead and Copper Rule Improvements (LCRI) take effect. Every CCR must include mandatory health-effects language about lead regardless of detection results (40 CFR § 141.154(d)).

Copper Copper shares the Lead and Copper Rule framework. Its action level is 1.3 mg/L. Like lead, copper is co-regulated under the LCRI and affects what your system must report on service line materials and sampling methodology. A dedicated page is planned for Phase 2.

Arsenic The MCL for arsenic is 0.010 mg/L. When detection falls between 0.005 mg/L and 0.010 mg/L, the CCR must include specific health-effects language noting the cancer risk and the balance EPA made between health protection and removal costs (40 CFR § 141.154(b)). A dedicated page is planned.

Nitrate The MCL for nitrate is 10 mg/L as nitrogen. When detection exceeds 5 mg/L but stays below the MCL, the CCR must include infant-safety language referencing "blue baby syndrome" (40 CFR § 141.154(c)). A dedicated page is planned.

Fluoride The MCL for fluoride is 4.0 mg/L; EPA's secondary standard is 2.0 mg/L. Fluoride is a universal CCR disclosure item for systems that add it or detect it above reporting thresholds. A dedicated page is planned.

Uranium The MCL for uranium is 30 µg/L. Uranium is most relevant for groundwater systems in the western United States and must be disclosed when detected. A dedicated page is planned for Phase 2.

Disinfection byproducts

Disinfection Byproducts (TTHMs and HAA5) Systems that use chlorine or other chemical disinfectants form byproducts as those disinfectants react with organic matter in source water. The two regulated families are Total Trihalomethanes (TTHMs, MCL 0.080 mg/L) and Haloacetic Acids (HAA5, MCL 0.060 mg/L). Compliance is calculated as a Locational Running Annual Average (LRAA). The CCR must report the range and average detected across all monitoring locations.

Chlorine residual Chlorine and chloramines are regulated as disinfectants — the limit is an MRDL (Maximum Residual Disinfectant Level), not an MCL. The MRDL for chlorine is 4.0 mg/L; for chloramines it is 4.0 mg/L as Cl2. A dedicated page covering chlorine residual reporting is planned for Phase 2.

Microbiological

Cryptosporidium Cryptosporidium is a protozoan regulated under the Long Term 2 Enhanced Surface Water Treatment Rule (LT2 ESWTR). It is not reported as an MCL because the rule uses a Treatment Technique approach. Every CCR must include boilerplate language about immunocompromised individuals and the heightened risk they face from waterborne pathogens (40 CFR § 141.154(a)). A dedicated page is planned for Phase 2.

Emerging contaminants

PFAS (Per- and Polyfluoroalkyl Substances) EPA finalized the first federal PFAS drinking water limits in April 2024 (89 FR 32532). The rule establishes five individual MCLs — PFOA at 4 ng/L, PFOS at 4 ng/L, PFNA at 10 ng/L, PFHxS at 10 ng/L, and HFPO-DA (GenX) at 10 ng/L — plus a Hazard Index of 1 for mixtures of PFHxS, PFNA, HFPO-DA, and PFBS. PFBS has no individual MCL; it is regulated only through the Hazard Index. Monitoring must be completed by April 26, 2027, with results appearing in CCRs beginning that year.

Radon Radon in drinking water is a source of inhalation exposure when water is used indoors. EPA has proposed but not finalized an MCL. Systems serving groundwater sources in radon-prone geology may need to monitor and disclose radon levels under state primacy rules even without a federal MCL. A dedicated page is planned for Phase 2.

Lead service lines — the new disclosure

Lead Service Line Inventory Starting with reports covering 2024 data, every CCR must include a statement confirming that a service line inventory has been prepared and instructions for consumers to access it (40 CFR § 141.153(h)(8)). This is a separate disclosure from the lead health-effects language — it covers inventory status and, if applicable, the system's service line replacement plan. Systems with no lead, galvanized-requiring-replacement, or unknown-status service lines must still include a written statement confirming that finding.

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Last reviewed: 2026-05-03. Next scheduled review: every 6 months or when EPA publishes a new NPDWR.