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1. Do I need a marine sewage treatment system (MSTS) or is a holding tank acceptable?
The minimum requirement for a vessel operating in Queensland waters is a macerating toilet, preferably fitted with a waste holding tank. If the vessel is moored or operating in waters where the discharge of macerated but untreated sewage is not allowed, a holding tank must be fitted unless the toilet is adequately and securely disabled in some way i.e. it is unable to be used. The accumulated waste in the holding tank must be retained on-board until it can be pumped out into an on-shore waste disposal facility or it can be discharged overboard when the vessel enters waters where the discharge of untreated waste is permitted.
Rather than waiting for access to pump-out facilities or having to move the vessel to an appropriate discharge area, many boat owners prefer to fit a marine sewage treatment system as it then allows them to conveniently dispose of the treated waste in the many areas located throughout Queensland waters where the discharge of treated waste is permitted. These systems also provide other benefits in terms of smaller holding tanks, less objectionable odours and a safer and more pleasant marine environment experience.
Different requirements apply in the various other Australian states. Please check the links page for further information.
2. My boat’s electrical system is 24 volts – do you have a suitable system?
NWS manufactures a range of systems and offers both 12 volt and 24 volt systems. Most other manufacturers also offer similar systems.
3. My vessel is fitted with a 240 volt system – do you have a suitable system?
NWS manufactures a range of larger systems using 240 volt pumps and electronics. Relays can also be supplied to operate 415 volt pumps if required.
4. What is a Grade C system (Queensland legislation)?
In simple terms, a Grade C system is a marine sewage treatment system that treats the waste through some form of chemical disinfection/sanitisation process. The criteria for a Grade C system is based primarily on the number of faecal coliforms (i.e. bactera) remaining in 100ml of the waste after treatment.
When operating with discharge permitted waters, a Grade C system still cannot be discharged within 926 metres of swimmers, aquaculture e.g. oyster leases, or a reef.
5. What is a Grade A system (Queensland legislation)?
Grade A systems, by comparison, must meet additional criteria such as suspended solids and biochemical oxygen demand (BOD), as well as the faecal coliform count. These systems usually use a combination of some form of aerobic digestion or filtration, followed by a disinfection/sanitisation process and therefore tend to be much larger systems.
When operating with discharge permitted waters, a Grade A system can be discharged adjacent to swimmers, aquaculture e.g. oyster leases, or a reef, due to the improved quality of the discharged effluent.
6. What is a Grade B system (Queensland legislation)?
Grade B systems have to meet the faecal coliform requirement as well as the total suspended solids requirement but not the BOD requirement. In practice, it has proven difficult to achieve this objective when compared to the Grade A and Grade C systems, and Grade B systems are not generally available.
7. What is Marpol?
MARPOL refers to the International Marine Pollution Convention. Please refer to the appropriate website for further information.
8. I have several toilets on my boat – can I direct the waste from all toilets into a single marine sewage treatment system?
This is possible, but the limiting factor is usually the number of people on board, rather than the number of toilets. Many luxury vessels have multiple toilets with very limited numbers of passengers and crew, and several toilets can readily be connected to a single MSTS in this case. Similarly, a vessel with many passengers but only two toilets is also self-limiting in terms of the volume of waste entering the MSTS.
9. I have an existing holding tank – can it be converted to a MSTS?
Yes – we supply “tankless” SANI-TANK kits, in both 12 and 24 volt format, that includes an adapter plate that can be attached to the top of an existing tank. The existing tank should preferably of high-density polyethylene (HDPE) construction or fibreglass. Metal tanks should be avoided as the chlorine solution used to treat the waste readily attacks most metal surfaces.
10. I cannot fit one of your standard tanks on my boat – what other sizes do you offer?
NWS has access to a number of plastics fabrication organisations that can manufacture tanks from HDPE to our specifications, for special requirements.
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