US Leather Tanning Effluent Guidelines — 40 CFR Part 425
- Citation
- 40 CFR Part 425
- Jurisdiction
- US
- Made by
- Environmental Protection Agency
- Instrument
- Regulation
- Status
- In force
What it requires (3 obligations)
This Part applies to any leather tanning and finishing facility which discharges or may discharge process wastewater pollutants to the waters of the United States, or which introduces or may introduce process wastewater pollutants into a publicly owned treatment works.
No date set Confirmed In force, dates fixed in published law
- Who it falls on
- Manufacturers
- Products
- Leather, textiles
- Markets
- US
Wording identical in structure to the textile mill Part at 40 CFR 410: discharging to a municipal treatment works does not put a tannery outside this Part, it changes which standards apply. "May discharge" brings a facility in before any discharge has occurred.
Quoted from 40 CFR § 425.01, "Applicability", eCFR snapshot 2026-08-01.
The Part divides tanneries into subcategories by PROCESS ROUTE, each with its own subpart and limitations: hair pulp, chrome tan, retan-wet finish; hair save, chrome tan, retan-wet finish; retan-wet finish-sides; no beamhouse; through-the-blue; shearling; pigskin; and retan-wet finish-splits. Each subpart states the operations it covers — the hair pulp subcategory, for example, applies to a tannery processing raw or cured cattle or cattle-like hides into finished leather by chemically dissolving the hide hair, chrome tanning and retan-wet finishing.
No date set Confirmed In force, dates fixed in published law
- Who it falls on
- Manufacturers
- Products
- Leather, textiles
- Markets
- US
Classification follows how the tannery UNHAIRS AND TANS, not what leather it sells — a tannery is in the hair pulp subcategory or the hair save one according to whether it dissolves the hair or recovers it. "No beamhouse" and "through-the-blue" are likewise process descriptions. A facility running more than one route may fall into more than one subcategory.
Quoted from the subpart headings of 40 CFR part 425 and from § 425.10 as the worked example.
Effluent limitations are set per subcategory and expressed in kg per 1,000 kg — pounds per 1,000 pounds — of RAW MATERIAL, that is the hide as received by the tannery. The parameters limited include BOD5, total suspended solids, oil and grease, total chromium, and pH within a stated range. Existing point sources must achieve the best practicable control technology limitations for their subpart except as provided in 40 CFR 125.30 to 125.32.
No date set Confirmed In force, dates fixed in published law
- Who it falls on
- Manufacturers
- Products
- Leather, textiles
- Markets
- US
The denominator is RAW MATERIAL, the hide as received — not finished leather. Yield does not help: a tannery that wastes less hide gets no extra headroom, because the divisor is what came in. TOTAL CHROMIUM appears here as a discharge limit, which is a different duty from the REACH Annex XVII restriction on chromium VI in leather articles recorded elsewhere in this register — same metal, different point in the process, different obligation. The figures quoted in the evidence note are ONE subcategory's BPT row, given to show the table's shape; every subpart has its own, and this record does not reproduce them.
Quoted from § 425.11 and the definition of "hide" at § 425.02(b). The BPT table for the hair pulp subcategory reads BOD5 9.3 / 4.2, TSS 13.4 / 6.1, oil and grease 3.9 / 1.7, total chromium 0.24 / 0.09, daily maximum and monthly average respectively, with pH within 6.0 to 9.0.
This is a register, not advice. It records what an instrument says and when it applies. Whether it applies to a particular company, product or shipment is a question for somebody who knows that business, and the answer is frequently not what the summary above would suggest.
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