What are the different types of required marine sanitation devices (MSDs) for boats with an installed flush type toilet?
There are three types of Coast Guard approved MSD’s as follows: Type I – Treats sewage before discharging by macerating or chopping the solids and then adding chemicals. Must meet specific standards concerning bacteria content and may show no visible solids. Type II – Provides a higher level of treatment than a type I MSD. Treats sewage biologically and separates the solids for pump-out or incineration. Type III – Holding Tank – A holding tank does not allow for the discharge of sewage. The waste is contained until it can be properly disposed of at a sewage pump-out station. Holding tanks are often fitted with a Y – valve which allows for the direct discharge of the contents when offshore (the three nautical mile off-shore regulation). The VDH recommends against the discharge of boat sewage overboard from any treatment or holding device.
