Compliance testing is required for drinking water and wastewater facilities that meet the definitions of regulated facilities under which CFR parts?

• A. 40 CFR 122 and 40 CFR 136
• B. 40 CFR 401 and 40 CFR 136
• C. 40 CFR 50 and 40 CFR 136
• D. 40 CFR 141 and 40 CFR 136

Answer: (D)

Drinking water compliance testing is built on two pieces: the standards that set what is considered safe, and the approved methods used to measure samples. The enforceable drinking water standards for public systems are in 40 CFR Part 141. To determine whether those standards are met, laboratories use EPA-approved analytical methods listed in 40 CFR Part 136. This pairing ensures both what must be achieved (the standards) and how to measure it (the methods) are defined consistently across facilities and labs. The other parts mentioned relate to different programs—such as wastewater permit requirements or air quality standards—so they don’t provide the framework for drinking water compliance testing.