Chapter 21:My Favorite Head
Types of Marine Sanitation Devices
It used to be that a toilet was a toilet and that a toilet in a boat was simply a head, and that was
that.Not anymore.These days, a toilet flushes into a marine sanitation device(MSD).This is
the sort of thing that happens when legislators get involved with practical matters.It’s impor-
tant to know about MSDs, however, because there are only three types approved for use on
boats.You must be certain you comply fully with the local regulations for MSDs in the area
you’re cruising or you can be in for big-time legal trouble.
Peculiarly (this is law after all), there don’t appear to be any restrictions that prohibit you
from hanging over the side of the boat and ...ah ...depositing directly overboard.Simi-
larly, an unattached bucket can be used in the vessel and dumped (at least that’s my understand-
ing, but you should check your local laws).What you can’t do is dump any sewage from any
source back into the water from an installedsystem (so don’t screw that bucket down).If you’re
not into this sort of roughing it, then you’ll have an installed MSD system,and it must comply
strictly with all federal and local regulations.
Type-I MSD
A Type-I MSD is one that treats sewage before discharge.One of the most common units is
Raritan’s LectraSan.The LectraSan goes for about $1,000 (2008) and requires salt water and a
fair amount of electric current to work.The PuraSan works in fresh water, or salt may be added
for freshwater use.Groco offers their Thermopure 2 Type-1 MSD system.
Regardless, all Type-1 MSDs reduce bacteria count to less than 1,000 per 100 milliliters,
which is pretty good but not as good as Type-2 systems.Type-I systems are acceptable for
discharge directly overboard on all boats under 65 feet (19.8 m) overall.You can do with no
holding tank at all, with one really big exception.There are more and more local (state and
city) 100 percent zero-discharge zones (no-discharge zones orNDZ).In such waters, you
can’t pump even Type-1 or Type-2 discharge overboard.Thus,if you have no holding tank,
you can’t cruise such areas, even with an approved Type-1 or Type-2 waste-treatment system
on board.
Type-2 MSD
Type-2 MSDs are also waste treatment systems.They meet more stringent requirements, how-
ever, allowing less than 1,000 parts per 100 milliliters of suspended particulate matter.This is al-
most clear.(There may be some color.) Bacteria count must be below 200 per 100 milliliters.
Boats over 65 feet (19.8 m) must have Type-2 MSDs if they intend to discharge overboard in
territorial waters.It’s a good thing that Type-1 MSDs are allowed on smaller boats, because
Type-2 systems cost a whole lot more—say, $6,000 or so (2008)—and they take up more room
and demand more power.Microphor, Humphries, and Galley Maid are three manufacturers of
Type-2 MSDs.
Type-3 MSD
A Type-3 MSD is a holding tank, period.A Porta Potti is a Type-3 MSD.Basically, holding tanks
are the only MSDs that are guaranteed to be acceptable on all waters,including all NDZs.The
drawbacks are obvious—they take up room, and they get full and have to be pumped out.If
you can’t find a pumpout station, you can pump out through your overboard discharge using a
macerator pump, but if you do so inside the three-mile limit, you’re breaking the law.