40 CFR § 429.171
Effluent limitations representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available (BPT)
June 9, 2020
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 representing the degree of effluent reduction attainable by the application of the best practicable control technology (BPT): Settleable solids shall be less than or equal to 0.2 ml/l and pH shall be between 6.0 and 9.0 at all times.