Sewage (often called ‘blackwater’) and graywater (the discharge from dishwashing, bathing and laundry) are waste streams on many boats. Both can contribute to pollution in your harbor that is unhealthy for both humans and aquatic life. In this module we’ll go over the basics of black and graywater and ways for boaters and harbor operators to manage these waste streams.
Untreated sewage discharges from a single weekend boater contributes the same amount of harmful bacteria to the water as does the treated sewage of 10,000 people!
It is illegal under federal law for anyone to discharge untreated sewage from a boat or vessel inside of 3 nautical miles!
A single vessel at sea discharging sewage may not impact human health, or the health of our shellfish beds, however multiple vessels in harbors, coves, inlets, and protected bays can have an impact.
What are the major concerns with sewage discharges?
- Spreading of disease.Disease-causing bacteria are found in sewage discharge and can make people sick when they come into contact with contaminated water. This doesn’t only pertain to swimmers – getting any sewage-polluted water in your mouth can make you sick.
- Aesthetics. Is there anything more unappealing than floating raw sewage? Enough said.
- Contamination of shellfish beds. Shellfish filter water, contaminants and all. Harmful bacteria can be processed by shellfish (including mussels, oysters and clams) and then infect people.
- Oxygen depletion. Decomposing sewage in the water uses a lot of oxygen, increasing what is called the “Biological Oxygen Demand” (BOD). The more oxygen used for decomposing sewage, the less available to fish and other aquatic organisms.
Consider how your facility can help boaters reduce their sewage discharges and protect the health of our coastal communities and shellfish beds.
QUESTION: Does your facility/community prohibit the discharge of treated AND untreated sewage in the harbor basin? If not, do you discourage legal discharges of treated sewage (from Type I or II MSDs) in your harbor?
marine sanitation devices (MSD)
It’s good to be generally familiar with the kinds of heads your customers may have on board. Any on-board toilet is required to be a USCG approved Marine Sanitation Device, or MSD. There are three types of MSDs - Type I, II and III. Scroll over each for an overview of how they work.
Types of Marine Sanitation Devices (MSDs):
- Type I
- Chops or macerates sewage before discharging. May add toxic chemicals.
- Only allowed on vessels less than 65 feet.
- Type II
- Treats sewage by biological means before discharging. Separates out solids.
- Cleaner but adds more chemicals than Type I
- Type III
- Does not discharge sewage; includes holding tanks, incinerators, and recirculating tanks.
- Waste is stored until it can be pumped out.
Sewage Management Options
What services do you offer customers to deal with their sewage waste? In addition to raising general awareness of the problems associated with sewage pollution, your harbor can work on two main fronts for improving sewage management - having working sewage pumpouts available for your customers, and having clean, functional upland restrooms. First we’ll look at pumpout options.
A pump-out is a device that is used to remove sewage from a vessel’s marine sanitation device (MSD). Pump-outs use one of three types of suction (diaphragm, peristaltic, or vacuum) to empty sewage from a vessel into a holding tank, or sometimes directly into a municipal waste system. The diaphragm systems are the most basic, ideal for smaller harbors that want to pump up to 25 gallons per minute. Peristaltic systems are ideal for use in pump-out boats, for integrated pump-out monitoring, and use integrated plumbing for easier installation. Vacuum systems are the largest and can handle large volumes of sewage, up to 100 gallons per minute, and include a 2-tank system that can continually pump out sewage into one tank and empty waste into a sewer system from another tank.
There are several different types of pump-outs available for use in harbors.
- Stationary dock-side pump-out: this system is mounted dock-side, has a long extendable hose that connects to the waste deck fitting of most vessels. Waste is pumped from a docked vessel into a holding tank on the dock, or in some cases flows directly into the city sewer system.
- Mobile dock pump-out: this pump-out is on a mobile cart and hosts its own holding tank. A hose and electric motor are used to pump sewage from a vessel into the cart-mounted holding tank, which can then be transferred to a larger holding tank or city sewer system.
- Pump-out boat: these systems are more mobile and can service larger vessels and travel within the harbor. The pump-out boat goes to the boater, and waste is pumped using on-board electric motors from a vessel directly into the pump-out boat’s holding tank, which is then taken to a fixed line on shore and emptied into sewer lines.
- Fixed line, direct sewer connection: this is the least mobile of all the pump-out options. Fixed lines are directly connected to the sewer system. Boaters use a mobile suction hose assembly to pump sewage from their vessel directly into the dock-side mounted fixed connection.
QUESTIONS: Does your facility have sewage pumpouts for boaters? If so, are they functional? Do boaters utilize them? Are they signed?
Encourage your customers to use upland restrooms when they’re in the harbor as often as possible. Ensuring your restrooms are clean and functional is a huge step towards customer satisfaction and improving sewage management at your facility! We know this can be a challenge, especially in some communities with security and other concerns. Talk with other departments and other harbors for ideas and solutions to allow for restrooms that are open to customers as much as possible.
QUESTION: Do you have functional and clean restrooms available for your customers? Are they available 24 hours a day?
Many of your customers have vessels with on-board heads and galleys. You may have liveaboards or even proper houseboats at your facility. Communicating with your customers about managing graywater and sewage is critically important to maintaining a clean and safe harbor for everyone.
Remind boaters with holding tanks that their Y-valves must be locked within 3 nautical miles and should never be bypassed for discharge in the harbor.
Talk to boaters about keeping their MSDs maintained and in good working order, and about the importance of using pumpouts when in the harbor.
best practices for sewage management
- Use on-shore restrooms as much as possible
- Maintain your MSD
- Always keep the Y-valve locked within 3 nautical miles
- Know where pumpouts are located at your harbor and how to use them. Communicate concerns with your harbor office.
Graywater from sinks, showers and laundry often contains detergents, other cleaning agents, and food scraps. Chemicals commonly found in graywater can be toxic to marine life and may contain nutrients that can lead to oxygen depletion in the harbor.
There are no federal regulations that deal with graywater from boats, but make sure that harbor staff are aware of the concerns with graywater and are keeping an eye out for discharges that could be minimized or avoided.
best practices for graywater management
- Store graywater when possible while in the harbor.
- Use on-shore restrooms and shower facilities.
- Reduce water usage as much as possible on-board while in the harbor.
- Clean off excess food scraps, fats and oils before washing dishes.
- Use soaps, detergents and other cleaners that are biodegradable, non-toxic and phosphate-free.
How do you communicate with customers about sewage and graywater management?
Options - signs, tip sheets, mailings, newspaper, radio, flyers, other: