Marine Sanitation Device




Marine Sanitation Device MSD Series
Ahead Tank Type II Marine Sanitation Devices are United States Coast Guard Certified in accordance with USCG Title 33 Code of Federal Regulations (CFR) 159 and complies with USCG Title 33 CFR 159.97 and may be installed aboard inspected vessels.

is the #1 Choice of Marine Sanitation Devices in the #2 Business


 is a biological aerobic (bacteria and air) Type II Marine Sanitation Device. Liquid and solid waste are removed from the water by bacteria naturally contained in sewage. The AHEAD TANK makes perfect environmental sense by working with nature to accelerate the normal biological process. With the addition of oxygen, the natural occurring bacteria breaks down and digest the solids. A mild disinfectant is added to kill any disease-causing bacteria prior to being discharged. AHEAD TANK has no moving parts that comes in contact with the sewage. This biological aerobic process is simple, effective, and ensures Reliable Odor Free Operation.




Sewage is aerated as soon as it enters the Aeration Chamber and mixes with the aerated liquid already in the Aeration Chamber. A fine bubble EPDM air diffuser injects air near the bottom of the Aeration Chamber so that the sewage remains in a state of aerobic decomposition. This aerated liquid contains the bacterial sludge that reacts with the sewage to start the reduction process. This movement created by the injected air helps mix the sewage with the bacterial sludge and prevents sludge and sewage solids from settling to the bottom. The air discharged from the surface of the liquid in the Aeration Chamber is vented to the atmosphere through a 1 ½’ FPT connection clearly labeled VENT in black on both sides of the tank.



The liquid displaced from the Aeration Chamber flows through small specially drilled holes at the front bottom side of the Clarification Chamber for further treatment. The suspended material and sewage solids that are too large to pass through the holes remain in the Aeration Chamber to be further reduced in size, as it continues to be mixed with the remaining aerated liquid and bacteria sludge. The liquid sludge and smaller waste material that enters the Clarification Chamber through the small holes is re-moved as the liquid flows upward through some biological filter media located inside the Clarification Chamber. Bacteria will grow on the surface of this biological filter media and produces a sticky, slimy film film that traps small particles of waste. Then the bacteria will consume the trapped particles of waste as their food supply. By the time the liquid reaches the top of the biological filter media it has passed through several layers of bacteria, ensuring that the sludge and waste removal process is completed. Any floating particles of waste that was not trapped and consumed by the bacteria that reaches the top of the biological filter media will be returned to the Aeration Chamber by means of an internal air lift pump. The clean water accumulates here until it is displaced through the crossover pipe connected to the Chlorination Chamber.



The clean water flowing out of the crossover pipe is directed through the PVC Chlorine Tablet Feeder located at the end of the cross over pipe. Here the clean water will come in contact with the Chlorine Disinfecting Tablets prior to entering into the Chlorination Chamber where it is held for a residence time sufficient to complete the disinfectant and final stage of the biological treatment process.



The disinfected water is then discharged overboard through a gravity overboard discharge connection. No internal pump is required if the AHEAD TANK is installed above the water line. However, if the AHEAD TANK is installed below the water line of the vessel it will be necessary to install an Automatic Waste Water Discharge System (This unit is sold separately). Ahead Sanitation Systems Inc. recommends the BEHIND TANK, a fully self-contained Automatic Waste Water Discharge System. The BEHIND TANK is constructed, and designed to be connected to the discharge of the AHEAD TANK at the same gravity water flow level. The BEHIND TANK comes complete with a Sump Pump (110 VAC or 220 VAC, single phase 60Hz), a Vertical Float Switch and Check Valve, all inside a Durable, Lightweight, Corrosion Proof and Compact, 18” X 18” X 18” LLPE polyethylene material tank.


Meets USCG Certification and IMO Standards Worldwide

  • Lightweight

  • Durable / Reliable

  • Simple to Install

  • Odor Free Operation

  • Uses Fresh or Salt Water

  • Gravity Overboard Discharge

  • Compact / Small Footprint

  • Corrosion Proof

  • Easy to Operate

  • Low Maintenance

  • Chemical Resistant

  • No Internal pump necessary


AHEAD TANK MSD ModelFlowrate (gal. per day)Number of People ( 24 hours)Disinfection SystemUSCG Approval No.
AT-6T56 gallons6Tablet159.015/9971/0
AT-12T88 gallons12Tablet159.015/9972/0
AT-16D88 gallons16Chlorine Solution159.015/9973/0
AT-20D110 gallons20Chlorine Solution159.015/9974/0

NOTE: The treatment capacity of the AHEAD TANK is expressed in the number of persons per 24 hours and depends on the type of toilet used with the system. Ahead Sanitation Systems Inc., recommends using SANIMARIN porcelain macerating toilets that have a normal flushing cycle that uses 0.58 gallons of water and is capable of pumping water 9.8 ft. vertically and 98 ft. horizontally for optimum treatment effectiveness. The SANIMARIN macerating toilets are offered in 110 VAC or 12 VDC.


operational functions are identical to that of the traditional larger heavy steel fabricated systems, but with the additional benefits of being rotationally molded from LLPE polyethylene. Its features include durability, smaller footprint, lightweight, simple to install and lower maintenance than the steel fabricated systems and at a fraction of the cost.

is the NEXT GENERATION of biological aerobic (bacteria & air) Type II Marine Sanitation Device. Its innovated design, incorporated with Advanced rotational molding technology, has enabled the AHEAD TANK to be the FIRST & ONLY Marine Sanitation Device constructed of LLPE, a Durable Lightweight Corrosion Proof polyethylene material. Its three separate sewage treatment chambers are rotationally molded into the internal structure of one single tank, an innovative State of the Art rotational molding process that no other company has been able to duplicate.

will be the LAST Marine Sanitation Device you will ever have to purchase. AHEAD TANK will not RUST nor CORRODE and it’s not affected by HARSH CHEMICALS , UV RAYS or the most EXTREME ENVIRONMENTAL CONDITIONS.

includes the following items at the time of purchase:

Quantity & Description of Items

  • Installation & Operation Manual
  • Hurricane Linear Air Pump
  • Air Hose & Hose Barb
  • Aluminum orange powder coated mounting brackets

Quantity & Description of Items

  • Pail of Sum uh dat Bio-Activator & Waste Degrader
  • Bottle of Sum uh dat Bio-Enhancer & Odor Controller
  • 10 lbs bucket of Blue Crystal Chlorine Disinfectant Tablets