Sewage and Waste


Untreated sewage from boats can spread gastroenteritis; contaminate shell fish beds and use up vital oxygen in the water. Human waste also contains phosphorous and nitrogen which both increase the levels of algae and reduce water clarity. Chemicals such as chlorine, formaldehyde, ammonium and zinc compounds, used to disinfect breakdown and deodorise waste, are toxic to marine life.

Clubs and training centres play an especially important role in educating the new boater as lessons learnt during their first RYA course are likely to become good habits throughout their boating life.

Discharge of boat sewage to coastal waters is regulated under MARPOL Annex V and whilst this only applies to recreational craft carrying 15 or more passengers, you only need 3 boats with 5 crew in each to produce the same amount of sewage. So it is certainly worth considering using your holding tank when out and about.

Sewage discharge from vessels in rivers, canals and lakes is regulated by many authorities and byelaws, but it is generally prudent to assume that discharges are not permitted. The Environment Agency has overarching powers of regulation.


Grey Water

Grey water discharge from sinks, showers and washing machines can be very damaging to sensitive aquatic life. Most washing detergents contain phosphates which encourage rapid algal growth. This in itself is can be a problem, but when the algae die, decomposition uses up valuable oxygen in the water. This eutrophic effect can cause fish and other aquatic life to suffocate.

Added to this the degreasers found in washing up liquids and soaps strip the natural oils from fish gills making it difficult for them to breathe and affecting their breeding cycle.



Litter has a major impact on wildlife, the main problems being entanglement and ingestion. It is estimated that over 50,000 marine mammals and 1 millions birds and turtles die every year from becoming tangled in or eating marine litter. Litter also diminishes the amenity value of an area and the cost to the tourism sector runs into millions of pounds. Plastics are the most prevalent beach litter material. Certain types of plastics are known to absorb chemicals from the surrounding environment, such as PCBs and heavy metals at concentrations up to 1 million times higher than in ocean waters. The ingestion of these toxins can have life threatening impacts upon marine wildlife.

It can be hard to identify the source of some water based litter. It is believed that recreational boating contributes very little to the total amount of marine and inland waterway litter (Marine Conservation Society Beach Watch Survey 2007). However it is extremely important that we all do our bit to prevent more litter from entering the marine environment.

The disposal of waste at sea is regulated by the International Maritime Organisation under MARPOL Annex IV and applies to all ships including small recreational craft. The law states that ships may not dump any plastic waste over the side. Other waste can only be disposed of overboard if ground up to a required standard and then only if more than 3 miles from land. A good rule of thumb for the recreational sailor is that the sea is not a dumping ground and no rubbish (with the exception of fresh fish and parts thereof) should be disposed of overboard.

The onus of the regulations falls on those who operate shore side facilities to enable vessels to land waste for disposal and to avoid the dumping of waste at sea. So it is important that clubs and training centres provide adequate disposal and recycling facilities.