Which Marine Sanitation Device is Right for You?

If you navigate in waters designated as a "No Discharge Zone," you only have one choice...you must retain all sewage, treated or not, for disposal ashore. Otherwise, choosing the type of Marine Sanitation Device that works best for you will depend on several factors. The answer to a few questions about how the boat is used should help you narrow the choices and determine optimal holding tank capacity:

• How many people are usually on board for a trip?
• Is the boat usually used for day trips or for longer periods and overnight cruises? Usually day trips do not generate much solid waste. Overnight trips virtually guarantee it.
• Does the boat anchor out overnight or tie up at a marina? When dockside, will you use the marina toilets?
• Are pumpout facilities located nearby?
• What are the boat’s design and space limitations for MSD installation?
• Is the electric power supply adequate for an electrically operated system?

Types of MSDs

TYPE I: Flow-through devices that use maceration and disinfection to treat waste prior to its discharge into the water; applicable for vessels 65 feet or less in length.

TYPE II: Similar to the Type I, but provides an advanced form of the same type of treatment and discharge wastes with lower fecal coliform counts and reduced suspended solids; applicable for vessels greater than 65 feet in length.

TYPE III: Commonly called a holding tank because sewage flushed from the marine head goes into a tank containing deodorizers and other chemicals. Waste in the holding tank is stored until it can be properly disposed of at a shore-side pumpout facility or serviced by a pumpout boat. Type III MSDs can be equipped with a Y-valve allowing the boater to direct sewage from the head into the holding tank, or send it directly overboard; applicable for any length vessel.