Greywater is the wastewater from, sinks, dishwashers, showers, hand basins, baths, and washing machines, and contains fats, oils, harmful chemicals, bleaches and germs that affect human health. Untreated greywater can have impacts on water quality and public health through high bacterial loads, nutrient discharge, biological oxygen demand and salinity impacts. Untreated greywater can turn septic if left untreated, in less than 24 hours.
Greywater discharge from vessels is a comparatively low contributor to overall water quality in the aquatic environment but is still an important source of pollution in localised areas that can and should be avoided. The number of vessels that provide luxury facilities with large greywater output such as ensuite bathrooms, dishwashers, washing machines and even spa baths are on the increase.
The greywater produced from these sources can be harmful to the receiving aquatic environment, especially in marinas, mooring locations and sheltered bays where the increasing number of overnight vessels with wastewater-producing facilities creates a higher concentration of wastewater. It is of most concern when released near shore in estuaries, bays, rivers and marinas.
Greywater discharge plumes may remain on the surface of aquatic environments and accumulate pollutants (particularly nutrients) around the vessel from which it is sourced or adjacent vessels. Excessive nutrients contribute to the growth of algae, which is known to cause problems for vessel operators, particularly within marina basins.
For example, water extracted from the River Murray is often only filtered for use in the kitchen sink; in many cases the water used for washing, showers and spas is taken directly from the River Murray and may therefore contain pathogens and other pollutants released by an adjacent vessel, or even one’s own.
In summary, the Code of practice for vessel and facility management (marine and inland waters) requires that vessel operators make an assessment of their vessel and the way in which they intend to operate it and undertake the most reasonable and practical measures outlined to manage greywater.
For many operators, this will mean making use of structural devices on board, such as fixed, fitted holding tanks and/or the introduction of treatment systems or simpler filtration components. For others, it could mean choosing to discontinue the use of onboard washing machines or dishwashers when in sensitive areas, not using phosphate detergents or maintaining their current behavioural practices of minimising the use of cooking oils and being vigilant in separating food stuffs from washing up water, etc.
Marine waters – requirements
Marine waters vessel operators can only release greywater into the ocean if:
- your boat is at least 1 nautical mile from land or any people in the water
- your boat is at least 3 nautical miles from an aquaculture lease (eg tuna, oyster and mussel farms)
- it does not have anything visibly floating in it (eg food scraps).
If you have treated the greywater to the standards listed in the code of practice then you can release it closer to land as long as you are not in a marina, canal or harbour, near people in the water or within 3 nautical miles of an aquaculture lease.
If a treatment system that achieves the above criteria cannot structurally be supported on the vessel, an in-line filter or strainer (where the drain and plumbing system permits) must be installed that prevents the discharge of any visible solids.
The code also lists recommended practices which marine waters vessel operators should adopt to better manage greywater onboard.
Inland waters – requirements
All vessels operating on inland waters are required to:
- contain all greywater (installation of a containment device for disposal into land-based waste management systems), or
- treat all greywater (installation of a greywater treatment system which can provide treatment to standards acceptable for freshwater discharge), or
- undergo behaviour changes (eg use of environmentally friendly detergents).
The code also lists recommended practices which inland waters vessel operators should adopt to better manage greywater onboard.
On July 1 2016, after months of trialling, assessment and consultation with industry, the EPA released a temporary exemption to the code which involves the alternative method for the treatment of greywater for inland vessels. This alternative method involves splitting greywater into two manageable streams, one from the galley (higher risk) and one from any other greywater producing facility, eg. vanity, shower, laundry tub (lower risk). Therefore, the following can be undertaken:
- split the greywater into two streams and manage them as follows: contain the galley greywater in a holding tank and treat (filter and disinfect) the other greywater producing facilities (eg vanity, shower, laundry tub) before discharging it.
Where vessel owners can prove to the satisfaction of the EPA that it is structurally impossible to install a containment or treatment system (eg cruisers or trailer-sailers), vessel owners are required to:
- contain galley waste (can be in existing blackwater tank)
- install a grease trap
- install in-line strainers for all other greywater production facilities.
EPA-recognised wastewater compliance inspectors
The EPA has recognised a number of vessel facilities and marine surveyors to:
- determine whether containment or treatment will be structurally impossible on board a vessel
- advise as to the modifications required to comply with the code of practice
- inspect vessels for greywater and blackwater compliance.
The following facilities and surveyors have been accredited:
- Mannum Marine (Greenings Landing) – (08) 8569 1609
- The Marina Hindmarsh Island – (08) 8555 7300
- Mannum Slipway and Moorings – (08) 8569 1620
- Long Island Marina – (08) 8532 6900
- Leo Vette (independent surveyor) – 0428 330 405
- Bill Leonard (independent surveyor) – 0400 824 816 or (08) 8532 1304
- Andrew McFarlane (Independent Surveyor) – 0413 525 242
- Mick Molnar (independent surveyor) – 0407 970 752
- Greywater requirements for vessels on inland waters
- FAQ – Greywater management requirements for vessels on inland waters
- Wastewater management requirements for vessels on marine waters
- FAQ – Wastewater management requirements for vessels on marine waters
- Rules for releasing wastewater from your vessel into marine waters
- Boating Industry Association
- Marine Information Pack – The EPA has produced a Marine Information Pack which contains all the information you need to know about managing your vessels wastewater on marine waters. Contact the EPA on (08) 8204 2004 or email for a pack to be sent to you.
- River vessel waste disposal options, Edition no.2
- Watch the video (18 MB)
- The use and management of spa baths on houseboats
The EPA does not endorse, approve nor recommend a product. It will recognise a product that meets the greywater discharge criteria listed in the code of practice. Recognised systems will be listed with the Boating Industry Association, tel (08) 8340 9641.