40 CFR § 141.503 - What does subpart T require?
---
identifier: "/us/cfr/t40/s141.503"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 141.503 - What does subpart T require?"
title_number: 40
title_name: "Protection of Environment"
section_number: "141.503"
section_name: "What does subpart T require?"
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "D"
subchapter_name: "WATER PROGRAMS"
part_number: "141"
part_name: "NATIONAL PRIMARY DRINKING WATER REGULATIONS"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "42 U.S.C. 300f, 300g-1, 300g-2, 300g-3, 300g-4, 300g-5, 300g-6, 300j-4, 300j-9, and 300j-11."
regulatory_source: "40 FR 59570, Dec. 24, 1975, unless otherwise noted."
cfr_part: "141"
---
# 141.503 What does subpart T require?
There are seven requirements of this subpart, and you must comply with all requirements that are applicable to your system. These requirements are:
(a) You must cover any finished water reservoir that you began to construct on or after March 15, 2002 as described in §§ 141.510 and 141.511;
(b) If your system is an unfiltered system, you must comply with the updated watershed control requirements described in §§ 141.520-141.522;
(c) If your system is a community or non-transient non-community water systems you must develop a disinfection profile as described in §§ 141.530-141.536;
(d) If your system is considering making a significant change to its disinfection practices, you must develop a disinfection benchmark and consult with the State for approval of the change as described in §§ 141.540-141.544;
(e) If your system is a filtered system, you must comply with the combined filter effluent requirements as described in §§ 141.550-141.553;
(f) If your system is a filtered system that uses conventional or direct filtration, you must comply with the individual filter turbidity requirements as described in §§ 141.560-141.564; and
(g) You must comply with the applicable reporting and recordkeeping requirements as described in §§ 141.570 and 141.571.