---
kind: "section"
citation: "40 C.F.R. § 437.40"
title: "40"
number: "437.40"
heading: "Applicability."
url: "https://uscodex.org/cfr/40/437.40"
---

# §437.40. Applicability.

- (a) Except as provided in § [437.1(b)](/cfr/40/437.1.md?p=b), [(c)](/cfr/40/437.1.md?p=c), or [(d)](/cfr/40/437.1.md?p=d) or in [paragraph (b)](#b) of this section, facilities that treat wastes subject to more than one of the previous subparts must comply with either provisions of this subpart or the applicable provisions of subpart [A](/cfr/40/subpartA.md), [B](/cfr/40/subpartB.md), or C. The provisions of this subpart are applicable to that portion of wastewater discharges from a centralized waste treatment facility that results from mixing any combination of treated or untreated waste otherwise subject to [subpart A](/cfr/40/subpartA.md), [subpart B](/cfr/40/subpartB.md), or [subpart C](/cfr/40/subpartC.md) of this part only if a facility requests the permit writer or control authority to develop [subpart D](/cfr/40/subpartD.md) limitations (or standards) and establishes that it provides equivalent treatment as defined in [§ 437.2(h)](/cfr/40/437.2.md?p=h).
- (b) In order to ensure appropriate treatment rather than dilution of dissimilar wastes, an NPDES permit writer or control authority may require a new or existing facility subject to [paragraph (a)](#a) of this section to achieve alternative effluent limitations or standards as defined in [§ 437.2 (b)](/cfr/40/437.2.md?p=b) in the following circumstances:
  - (1) The facility receives, on a continuing basis, flows of process wastewater from five or fewer facilities subject to [40 CFR](/cfr/40.md) subchapter N limitations and standards; and
  - (2) The process wastewater flows received for treatment at the facility have relatively consistent pollutant profiles.

## Notes

### Authority

Authority: 33 U.S.C. 1311, 1314, 1316, 1317, 1318, 1342, and 1361.

### Source

Source: 65 FR 81300, Dec. 22, 2000, unless otherwise noted.