Code of Federal Regulations > Title 40 > Chapter I > Part 141 - PART 141—NATIONAL PRIMARY DRINKING WATER REGULATIONS

U.S. Code of Federal Regulations

Regulations most recently checked for updates: Jan 21, 2026

Subpart A [§ 141.1 - § 141.6] - Subpart A—General

Subpart B [§ 141.11 - § 141.13] - Subpart B—Maximum Contaminant Levels

Subpart C [§ 141.21 - § 141.29] - Subpart C—Monitoring and Analytical Requirements

Subpart D [§ 141.31 - § 141.35] - Subpart D—Reporting and Recordkeeping

Subpart E [§ 141.40 - § 141.42] - Subpart E—Special Regulations, Including Monitoring

Subpart F [§ 141.50 - § 141.55] - Subpart F—Maximum Contaminant Level Goals and Maximum Residual Disinfectant Level Goals

Subpart G [§ 141.60 - § 141.66] - Subpart G—National Primary Drinking Water Regulations: Maximum Contaminant Levels and Maximum Residual Disinfectant Levels

Subpart H [§ 141.70 - § 141.76] - Subpart H—Filtration and Disinfection

Subpart I [§ 141.80 - § 141.93] - Subpart I—Control of Lead and Copper

Subpart J [§ 141.100 - § 141.101] - Subpart J—Use of Non-Centralized Treatment Devices

Subpart K [§ 141.110 - § 141.111] - Subpart K—Treatment Techniques

Subpart L [§ 141.130 - § 141.135] - Subpart L—Disinfectant Residuals, Disinfection Byproducts, and Disinfection Byproduct Precursors

Subpart M - Subparts M-N [Reserved]

Subpart O [§ 141.151 - § 141.156] - Subpart O—Consumer Confidence Reports

Subpart P [§ 141.170 - § 141.175] - Subpart P—Enhanced Filtration and Disinfection—Systems Serving 10,000 or More People

Subpart Q [§ 141.201 - § 141.211] - Subpart Q—Public Notification of Drinking Water Violations

Subpart R - Subpart R [Reserved]

Subpart S [§ 141.400 - § 141.405] - Subpart S—Ground Water Rule

Subpart T [§ 141.500 - § 141.571] - Subpart T—Enhanced Filtration and Disinfection—Systems Serving Fewer Than 10,000 People

Subpart U [§ 141.600 - § 141.605] - Subpart U—Initial Distribution System Evaluations

Subpart V [§ 141.620 - § 141.629] - Subpart V—Stage 2 Disinfection Byproducts Requirements

Subpart W [§ 141.700 - § 141.723] - Subpart W—Enhanced Treatment for Cryptosporidium

Subpart X [§ 141.800 - § 141.810] - Subpart X—Aircraft Drinking Water Rule

Subpart Y [§ 141.851 - § 141.861] - Subpart Y—Revised Total Coliform Rule

Subpart Z [§ 141.900 - § 141.905] - and Polyfluoroalkyl Substances (PFAS)