{"data":{"id":"us/40-cfr-471.81","jurisdiction":"us","citation":"40 CFR 471.81","heading":"Effluent limitations representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available (BPT).","body":"Except as provided in 40 CFR 125.30 through 125.32, any existing point source subject to this subpart must achieve the following effluent limitations for the process operations representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available (BPT):\n(a) Rolling spent neat oils—subpart H—BPT. There shall be no discharge of process wastewater pollutants.\n(b) Rolling spent emulsions.\nSubpart H—BPT\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/off-kg (pounds per million off-pounds) of zinc rolled with emulsions\nChromium 0.0006 0.0003\nCopper 0.003 0.002\nCyanide 0.0004 0.0002\nZinc 0.002 0.0009\nOil and grease 0.028 0.017\nTSS 0.057 0.027\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(c) Rolling contact cooling water.\nSubpart H—BPT\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/off-kg (pounds per million off-pounds) of zinc rolled with contact cooling water\nChromium 0.236 0.0097\nCopper 1.02 0.536\nCyanide 0.156 0.065\nZinc 0.783 0.327\nOil and grease 10.7 6.43\nTSS 22.0 10.5\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(d) Drawing spent emulsions.\nSubpart H—BPT\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/off-kg (pounds per million off-pounds) of zinc drawn with emulsions\nChromium 0.003 0.001\nCopper 0.011 0.006\nCyanide 0.002 0.0007\nZinc 0.009 0.004\nOil and grease 0.116 0.070\nTSS 0.238 0.113\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(e) Direct chill casting contact cooling water.\nSubpart H—BPT\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/off-kg (pounds per million off-pounds) of zinc cast by the direct chill method\nChromium 0.222 0.091\nCopper 0.960 0.505\nCyanide 0.147 0.061\nZinc 0.738 0.308\nOil and grease 10.1 6.06\nTSS 20.7 9.85\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(f) Stationary casting contact cooling water—subpart H—BPT. There shall be no discharge of process wastewater pollutants.\n(g) Heat treatment contact cooling water.\nSubpart H—BPT\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/off-kg (pounds per million off-pounds) of zinc heat treated\nChromium 0.336 0.138\nCopper 1.45 0.763\nCyanide 0.221 0.092\nZinc 1.12 0.466\nOil and grease 15.3 9.16\nTSS 31.3 14.9\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(h) Surface treatment spent baths.\nSubpart H—BPT\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/off-kg (pounds per million off-pounds) of zinc surface treated\nChromium 0.039 0.016\nCopper 0.169 0.089\nCyanide 0.026 0.011\nZinc 0.130 0.054\nOil and grease 1.78 1.07\nTSS 3.64 1.73\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(i) Surface treatment rinse.\nSubpart H—BPT\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/off-kg (pounds per million off-pounds) of zinc surface treated\nChromium 1.58 0.645\nCopper 6.80 3.58\nCyanide 1.04 0.430\nZinc 5.23 2.19\nOil and grease 71.6 43.0\nTSS 147 69.8\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(j) Alkaline cleaning spent baths.\nSubpart H—BPT\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/off-kg (pounds per million off-pounds) of zinc alkaline cleaned\nChromium 0.002 0.0007\nCopper 0.007 0.004\nCyanide 0.001 0.0004\nZinc 0.005 0.002\nOil and grease 0.071 0.043\nTSS 0.146 0.069\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(k) Alkaline cleaning rinse.\nSubpart H—BPT\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/off-kg (pounds per million off-pounds) of zinc alkaline cleaned\nChromium 0.744 0.304\nCopper 3.21 1.69\nCyanide 0.490 0.203\nZinc 2.47 1.03\nOil and grease 33.8 20.3\nTSS 69.3 33.0\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(l) Sawing or grinding spent emulsions.\nSubpart H—BPT\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/off-kg (pounds per million off-pounds) of zinc sawed or ground with emulsions\nChromium 0.011 0.005\nCopper 0.045 0.024\nCyanide 0.007 0.003\nZinc 0.035 0.015\nOil and grease 0.476 0.286\nTSS 0.976 0.464\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(m) Electrocoating rinse.\nSubpart H—BPT\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/off-kg (pounds per million off-pounds) of zinc electrocoated\nChromium 1.01 0.412\nCopper 4.35 2.29\nCyanide 0.664 0.275\nZinc 3.35 1.40\nOil and grease 45.8 27.5\nTSS 93.9 44.7\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(n) Degreasing spent solvents—subpart H—BPT. There shall be no discharge of process wastewater pollutants.","path":["Title 40—Protection of Environment","CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY","SUBCHAPTER N—EFFLUENT GUIDELINES AND STANDARDS","PART 471—NONFERROUS METALS FORMING AND METAL POWDERS POINT SOURCE CATEGORY","Subpart H—Zinc Forming Subcategory"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-40.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:04Z","sha256":"07f8bb957d08d4fb3df52c4e46235f86cb7eb84694ce4ca32965f918dec48959","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-471.80","next":"us/40-cfr-471.82"},"notice":"GroundRules: Original legal text. Not legal advice."}