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Selecting Among Different Sanitation Systems
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The Requirements
The U.S. Coast Guard requires that all boats with installed toilet
facilities have some means of treating and/or storing waste (a.k.a. an MSD, or Marine
Sanitation Device) onboard. Only the storage/treatment device needs to meet Coast Guard
approval; system design can be determined by the boat owner.
Federal regulations designate three types of
discharge "zones" in U.S. waters. Over three miles offshore, you can discharge
waste directly overboard. Inside the three-mile limit, it is illegal to dump raw
(untreated) sewage. In these areas, boaters may discharge waste only if it has been
"sanitized" by an onboard treatment device. Otherwise, it must be contained
onboard and discharged at a pump-out station (which, in many cases, means it will get a
modest amount of treatment and then get pumped back into the water). Some inland waterways
and coastal areas have been designated "zero discharge" zones, which means that
overboard discharge of any kind is illegal. Consult the Coast Guard to find out the waste
discharge rules for the waterways on which you will be operating.
 The Portable Head Method
This is a solution for thousands of "weekend" or trailer
boats that need a way to hold limited amounts of waste. They aren't fun to take on shore
and dump, but they eliminate the need to install permanent plumbing and are inexpensive.
 The Holding Tank/No Discharge Method
For areas with pump-out facilities, a holding tank connected between your head's
discharge and a through-deck fitting is inexpensive and meets the requirements of the law.
We offer holding tanks as small as 3 gallons, although we strongly recommend installing a
large tank if possible. The drawback with this method is that you have no recourse if your
tank is full and you cannot find a pump-out station.
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Head & Holding Tank Treatments |
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Holding
tank treatments combine deodorants and germ killers to mask or eliminate offensive odors
created as waste is broken down. They come in four basic formulations.
Chemical
treatments, the most common, kill bacteria immediately. They very effectively
control odors by masking smells with deodorant. Although relatively inexpensive compared
to other treatments, chemicals must be added regularly. They are not designed to dissolve
waste and they are the least environmentally friendly.
Enzyme
treatments accelerate the digestion of organic materials in waste and neutralize
odors at the same time. Their toxicity is extremely low. They work quickly and
completely emulsify paper and sewage. They must be added regularly and they have a limited
range of effectiveness in terms of temperature and pH. Enzymes require a tank free from
residuals of other treatment products.
Nitrate
treatments provide an interesting alternative. Oxygen is vital to bacteria in the
process of breaking down organic waste. When little air is present, as in most holding
tanks, bacteria derives the oxygen from sulfates in the waste, which produces hydrogen
sulfide (stinky!) gas. When nitrates are introduced, they act as nutrients for the
bacteria, providing an alternative source of oxygen, which results in the production of
nitrogen (odorless) gas. Nitrates are environmentally friendly. They speed up the
breakdown process and eliminate odors. They require a tank free of the residuals from
other products. They are expensive relative to other treatments.
Bioactive
treatments contain live aerobic bacteria, which break down waste, reproduce and
crowd out anaerobic (odor-producing) bacteria. They, too, are environmentally friendly.
Like enzymes, bioactive treatments emulsify paper and sewage completely. Unlike other
treatments, they multiply and continue to work long after treatment is complete,
eliminating the need to add more between pump outs. However, the microbes require a
well-ventilated holding tank to survive. The tank must be free of residuals. Although
initially expensive, bioactive treatments become more cost effective over time because of
bacteria propagation
A Word
About Bilge Pump Ratings
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There is a good deal
of misinformation in the world of centrifugal bilge pumps, at least between
"advertised" capacity and actual capacity. Boy, was it great to read this:
"Submersible centrifugal bilge
pumps dominate the electric bilge pump market, and with good reason. They are simple,
reliable, easy to install, and cheap. The gap between real-world performance and the
nominal output of these pumps, however, is so great that in our opinion it borders on the
irresponsible. Like the warning on packs of cigarettes, every centrifugal bilge pump
should have the following emblazoned on the pump: 'Warning: this pump's nominal capacity
is rated at open flow, with no lift and no discharge hose attached. In actual
installations aboard a boat, the pump will never achieve this rate of flow.'
"The only pumps which have
warnings are West Marine's house brand pumps, which give flow rates at various lifts and
various system voltages. This information, permanently attached to the pump, should be an
industry standard. It would reduce the misleading pump capacity claims that plague the
electric bilge pump industry."
(Nick Nicholson, Practical Sailor,
October 1, 1997)
Our thanks to Nick Nicholson and
Practical Sailor for helping to set the record straight, and for confirming something we
have believed in strongly for years. Due to reductions in flow caused by lift, hose
length, indirect hose runs, and other factors, actual capacity is usually no more than
half, and sometimes as little as one-third the "advertised" rating. Buyer
beware! Be sure to consider these installation factors, and buy the largest capacity
pump you can fit in the space. |
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Sanipottie Portable
JABSCO Compact Marine Head
Sealand Head Treatment
Works instantly
to control ordor. For all makes of marine and recirculating toilets
Wor
Puriclean Water Purifier
Rule Submersible
Bilge Pump
Thirsty-Mate
Hand Bilge Pump
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