Treatment Technique (TT)

A treatment technique is an enforceable procedure or level of technological performance that a public water system must follow to control a contaminant when EPA cannot establish a numerical limit — defined at 40 CFR § 141.2.

Where you'll see it on a CCR

TT violations appear on your Consumer Confidence Report differently than MCL violations. An MCL violation names a contaminant and a measured concentration that exceeded a legal threshold. A TT violation names a required procedure the system failed to perform — for example, failing to maintain a minimum disinfectant residual, or skipping required tap monitoring under the Lead and Copper Rule. The violation tells you what the system didn't do, not what level of contamination resulted. Both types must be reported under 40 CFR § 141.153.

Why some contaminants use TT instead of MCL

The Safe Drinking Water Act authorizes EPA to set a treatment technique instead of a maximum contaminant level when establishing an MCL is not "economically or technologically feasible" — SDWA § 1412(b)(7)(A), codified at 42 U.S.C. § 300f(1)(C). For certain microbial contaminants, routine monitoring at the tap can't reliably detect a pathogen before a customer is exposed. For lead and copper, the problem isn't a fixed source concentration — it's the reaction between water chemistry and the plumbing materials in a specific building. In both cases, controlling the process is more protective than measuring the outcome.

Examples of TT requirements

• Lead and Copper Rule (LCR/LCRI). Systems must optimize corrosion control treatment, conduct tap monitoring at high-risk sites, and replace lead service lines on a required schedule. The action level for lead (15 µg/L under current rules, dropping to 10 µg/L when the Lead and Copper Rule Improvements take effect November 1, 2027) triggers additional TT obligations — it does not by itself constitute a violation. See lead contaminant page for more.
• Surface Water Treatment Rule (SWTR). Systems drawing from rivers, lakes, or reservoirs must filter and disinfect source water. The rule specifies minimum log-inactivation/removal credits for Giardia and viruses. Failing to achieve those credits is a TT violation.
• Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR). Systems are "binned" based on measured Cryptosporidium levels in their source water. Each bin carries a required log-removal or inactivation target. The system must meet that target continuously — there is no single detectable threshold that constitutes an MCL.

Related terms

• Maximum Contaminant Level (MCL) — a numerical limit on a contaminant's concentration, used when measurement is feasible
• Action Level — a concentration threshold that triggers additional TT requirements under the Lead and Copper Rule
• CCR overview — how all violation types are reported to customers

Citations

• 40 CFR § 141.2 — Definitions (treatment technique): https://www.law.cornell.edu/cfr/text/40/141.2
• 40 CFR § 141.153 — Content of the report (violation reporting): https://www.law.cornell.edu/cfr/text/40/141.153
• 42 U.S.C. § 300f — SDWA definitions (§ 300f(1)(C) TT authority): https://www.law.cornell.edu/uscode/text/42/300f
• 42 U.S.C. § 300g-1 — SDWA § 1412 (standard-setting authority): https://www.law.cornell.edu/uscode/text/42/300g-1

Review marker: Verified against 40 CFR § 141.2, § 141.153, SDWA § 1412(b)(7)(A), LCRI FR notice 2024-23549 (89 FR 86416, Oct 30 2024). LCRI compliance date confirmed as November 1, 2027. Last reviewed 2026-05-03.