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(Regulation VII/10.3)
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ESTIMATING GUIDELINES FOR HOLDING TANK CAPACITY
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1 These calculations shall be used as guidelines, as capacities are not
mandated. The capacity of each Marine Sanitation Device (MSD) should be
evaluated in terms of the vessel’s size, route, service, and particular
circumstances. These capacities consider only “black-water” toilet drains. On
the average, each person will produce 0.4 gallons of waste per day.
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2 Flush Rate. Table A9-1 estimates the water used per flush by
different toilet systems.
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TABLE A9-1
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APPROXIMATE FLUSH CAPACITIES FOR VESSEL TOILETS DRAINING TO MARINE
SANITATION DEVICES
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System Type
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Gallons per flush
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Conventional
(flushometer)
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5.0
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Recirculating
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0.1
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Vacuum
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0.3
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Hand Pump
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0.5
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Electric
Pump
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1.0
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3 Wastewater produced. Table A9-2 estimates the gallons of
wastewater produced per person per day, based on the plumbing type, and the way
the boat operates.
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TABLE A9-2
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GALLONS OF WASTEWATER PER PERSON PER DAY BASED ON PLUMBING TYPE
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| Trip Length
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User
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Conv.
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Recirc.
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Vacuum
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Band Pump
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Electric
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| LONG
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Crew
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25.4
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0.5
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1.9
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2.9
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5.4
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| (Note 1)
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Pax
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25.4
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0.5
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1.9
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2.9
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5.4
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| MEDIUM
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Crew
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25.4
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0.5
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1.9
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2.9
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5.4
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Pax
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8.3
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0.17
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1.9
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1.0
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1.8
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| SHORT
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Crew
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12.7
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0.25
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0.95
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1.95
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2.7
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Pax
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6.35
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0.25
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0.5
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0.7
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1.35
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Note
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1 Crew and passengers aboard 24 hour/day.
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2 Crew aboard 24-hour/day; 2 groups of passengers aboard for 4 hours
each (2 trips/day), each passenger using facilities once.
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3 All crew aboard 12 hour/day; 6 groups of passengers aboard for 2 hours
(6 trips per day), one fourth of passengers using facilities once.
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