Grey water is wastewater that has been used for washing, laundering, bathing or showering. This includes water containing dissolved or undissolved by-products such as fat and oil, food scraps, household chemicals, soap and detergent rich in phosphate and nitrate, and microbiological pathogens (eg bacteria and viruses).
Grey water discharge from vessels is a comparatively low contributor to overall water quality in the marine 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 such as ensuite bathrooms, dishwashers, washing machines and even spa baths are on the increase.
The grey water produced from these sources can be harmful to the receiving aquatic environment and other marine users, especially in marinas 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.
Grey water discharge plumes may remain on the surface of marine waters 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 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 grey water.
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 vessel operators can only release grey waterinto the ocean if:
- your boat is at least one nautical mile from land or any people in the water
- your boat is at least three 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 grey water 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 three 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 grey water onboard. For vessels that through their operation by users will not generate black water, there are no requirements.
Under clause 5.18 of the Code of practice for vessel and facility management (marine and inland waters), vessel owners are required to contain all greywater produced on board, or only discharge greywater if the following criteria are met (dilution is not acceptable):
- suspended solids less than 50 mg/L
- a total grease content of less than 25 mg/L
- nitrogen content less than 10 mg/L
- phosphorous content less than 1 mg/L
- Enterococci of less than 40 cells per 100 mL, and
- Biochemical oxygen demand is reduced by digestion, oxidation or other recognised treatment method
Usually, these criteria are only met via treatment. Containment options can include containing greywater in existing blackwater tanks, or installing greywater tanks of a suitable size. Appendices 3 and 4 of the code of practice outlines the requirements for installing containment tanks.
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); or
- install a grease trap; and
- install in-line strainers for all other greywater production facilities.
Owners of permanently occupied and commercial vessels, or vessels with multiple bathrooms, ensuites or showers, and/or dishwashers, washing machines, spas are required to contain or treat all greywater produced on board the vessel.
All vessel owners should also adopt environmentally friendly practices (eg using low flow devices, biodegradable detergents and scraping food waste into a bin).
The code also lists recommended practices which inland waters vessel operators should adopt to better manage greywater onboard.
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
- Morgan waterfront Marina/Slipway - (08) 8540 2257
- 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
Greywater treatment systems
Australian Standard for Greywater Treatment Systems for vessels operated on inland waters (AS 4995)
This Australian Standard—the first of its kind— sets out specifications for the design, construction, installation and operation of onboard greywater treatment systems to minimise the environmental and public health risks caused by untreated greywater discharge.
It was developed to support the code of practice introduced by the South Australian Government in 2008 to help reduce potential risks posed by the discharge of greywater into the Murray River and South Australian waterways.
AS 4995 is an industry benchmark developed to minimise the development and installation of substandard units that do not meet the requirements of the Code. AS 4995 assists boat builders, manufacturers, vessel owners and operators in complying with this greywater management option
A copy of the Australian Standard can be found here (AS 4995–2009).
- Wastewater management requirements for vessels on marine waters – frequently asked questions
- Wastewater management requirements for vessels on marine waters
- Rules for releasing wastewater from your vessel into marine waters
- Boating Industry Association of SA
- 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)
- Boating Industry Association of SA
- The use and management of spa baths on houseboats
The EPA does not endorse, approve or recommend a product. It will recognise a product that meets the grey water discharge criteria listed in the code of practice. Recognised systems will be listed with the Boating Association of SA. For more information please contact BIASA on (08) 8212 6000 or visit their website.
A short video of the grey water project was screened at the SA Premier's Awards in 2009, where the EPA was presented with the award for 'Fostering Creativity and Innovation' in the development of the code and stimulating the development of 'world first' greywater treatment technology.