40 CFR § 437.31 - Effluent limitations attainable by the application of the best practicable control technology currently available (BPT).

---
identifier: "/us/cfr/t40/s437.31"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 437.31 - Effluent limitations attainable by the application of the best practicable control technology currently available (BPT)."
title_number: 40
title_name: "Protection of Environment"
section_number: "437.31"
section_name: "Effluent limitations attainable by the application of the best practicable control technology currently available (BPT)."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "N"
subchapter_name: "EFFLUENT GUIDELINES AND STANDARDS"
part_number: "437"
part_name: "THE CENTRALIZED WASTE TREATMENT POINT SOURCE CATEGORY"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "33 U.S.C. 1311, 1314, 1316, 1317, 1318, 1342, and 1361."
regulatory_source: "65 FR 81300, Dec. 22, 2000, unless otherwise noted."
cfr_part: "437"
---


# 437.31 Effluent limitations attainable by the application of the best practicable control technology currently available (BPT).

Except as provided in 40 CFR 125.30 through 125.32 or § 437.30(b), any existing point source subject to this subpart must achieve the following effluent limitations representing the application of BPT:

BPT Limitations

| Regulatedparameter | Maximum daily | Maximum monthly avg. |
| --- | --- | --- |
|  |  |  |
| BOD | 163 | 53.0 |
| pH | () | () |
| TSS | 216 | 61.3 |
|  |  |  |
| Copper | 0.865 | 0.757 |
| Zinc | 0.497 | 0.420 |
|  |  |  |
| Acetone | 30.2 | 7.97 |
| Acetophenone | 0.114 | 0.0562 |
| 2-Butanone | 4.81 | 1.85 |
| o-Cresol | 1.92 | 0.561 |
| p-Cresol | 0.698 | 0.205 |
| Phenol | 3.65 | 1.08 |
| Pyridine | 0.370 | 0.182 |
| 2,4,6-Trichlorophenol | 0.155 | 0.106 |
| mg/L (ppm). |  |  |
| Within the range 6 to 9. |  |  |

[65 FR 81300, Dec. 22, 2000, as amended at 68 FR 71023, Dec. 22, 2003]