Section 139.21 - Graywater systems(a) The requirements in paragraphs (b) through (g) of this section apply to discharges of graywater except for graywater from any commercial vessel on the Great Lakes that is subject to the requirements in 40 CFR part 140 and 33 CFR part 159.(b) The introduction of kitchen waste, food, oils, and oily residues to the graywater system must be minimized.(c) Any soaps, cleaners, detergents, and other substances used by vessel operators or provided by vessel operators to persons onboard and discharged in graywater must be minimally-toxic, phosphate-free, and biodegradable.(d) The discharge of graywater is prohibited from any vessel:(1) Within 3 NM from shore that voyages at least 3 NM from shore and has remaining available graywater storage capacity, unless the discharge meets the standards in paragraph (f) of this section; and(2) Within 1 NM from shore that voyages at least 1 NM from shore but not beyond 3 NM from shore and has remaining available graywater storage capacity, unless the discharge meets the standards in paragraph (f) of this section.(e) The discharge of graywater from the following vessels must meet the numeric discharge standard established in paragraph (f) of this section:(1) Any new vessel of 400 GT (400 GRT if GT is not assigned) and above that is certificated to carry 15 or more persons and provides overnight accommodations to those persons;(2) Any passenger vessel, excluding any ferry, with overnight accommodations for 500 or more persons;(3) Any passenger vessel, excluding any ferry, with overnight accommodations for 100-499 persons unless the vessel was constructed before December 19, 2008, and does not voyage beyond 1 NM from shore; and(4) Any new ferry authorized by the Secretary to carry 250 or more persons.(f) A vessel identified in paragraph (d) or (e) of this section that is discharging graywater must meet the following numeric discharge standard:(1)Fecal coliform.(i) The 30-day geometric mean must not exceed 20 cfu, or MPN, per 100 mL.(ii) Greater than 90% of samples must not exceed 40 cfu, or MPN, per 100 mL during any 30-day period.(2)BOD5.(i) The 30-day average must not exceed 30 mg/L.(ii) The 7-day average must not exceed 45 mg/L.(3)Suspended solids.(i) The 30-day average must not exceed 30 mg/L.(ii) The 7-day average must not exceed 45 mg/L.(4)pH.(i) Must be maintained between 6.0 and 9.0.(5) Total residual oxidizers.(i) For any discharge from a graywater system using chlorine, total residual oxidizers must not exceed 10.0 [MICRO]g/L.(g) Unless from a vessel subject to paragraph (e) of this section, the discharge of graywater from any vessel operating on the Great Lakes that is not a commercial vessel must not exceed 200 fecal coliform forming units per 100 milliliters and contain no more than 150 milligrams per liter of suspended solids.(h) Additional standards applicable to discharges from graywater systems when a vessel is operating in federally-protected waters are contained in § 139.40(h).