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Black Water


With more and more of us taking to the water each year it is important we all know how to deal with our waste in a responsible manner. It is no longer acceptable to pump waste out whenever and wherever it suits and it is our responsibility to consider the effects this may have on the surrounding environment.


Sewage discharges are likely to become less common over time as, since 2016, the Recreational Craft Directive (RCD) has required all new vessels to have provision for a holding tank to be fitted.


Levels of sewage input from recreational craft are thought to be relatively small compared to direct inputs from sewage treatment works but the effects are serious and can potentially affect water quality.


Impacts of raw sewage discharge:


  • Unsightly and can smell
  • A serious health risk to humans if ingested due to bacteria content,g. E-Coli
  • Adversely affects shellfish
  • Depletes oxygen levels in the water as it decomposes.
  • Leads to nutrient enrichment and algal blooms which can block out sunlight and prevent other aquatic species from surviving.


As a result, it is our responsibility as recreational boaters to be aware of the rules regulating the disposal of waste and sewage.


Inland Waters


Sewage discharge is prohibited by law on inland waterways in the UK. The Canal & River Trust provides an interactive pump out facility map.


Coastal Waters


Regulations regarding the discharge of sewage are gradually increasing, however as yet there is no international convention which requires private pleasure craft to fit a holding tank, with the application for the latest wording for MARPOL (Marine pollution) chapter IV, only applying to vessels which exceed 400GT or carry more than 15 passengers.


Although no specific provisions are made for smaller pleasure vessels, it is important to consider the impact of discharging raw sewage from a sea toilet or holding tank into the sea. It is best practice to return all waste generated on board to shore waste reception facilities where possible.


There are many other countries where the direct overboard discharge of sewage is prohibited by the authorities. The provision of holding tanks of sufficient capacity to store waste for discharge to shore facilities may be needed for a vessel to comply with legislation in these countries.


Onshore facilities:


  • Use land based facilities wherever possible.
  • Always use pump out facilities or sewerage facilities to dispose of black water. Find out where your nearest pump out facility is by using The Green Blue’s Pump-Out Directory [Link to ‘Pump Out Directory’ webpage 10.1.3]


  • Choose or encourage your marina, boatyard or harbour to install a pump out facility for boaters to use.


On-board facilities:


  • Use a closed toilet system such as a holding tank or chemical toilet.
  • Composting toilets are a great idea to cut down on waste and chemicals, but please dispose of black water at facilities rather than discharging to water or depositing on land.
  • Consider fitting a holding tank, it is law in some European countries and required when using inland waterways that adjoin coastal waterways in the UK e.g. the Caledonian Canal, Scotland. If fitting a holding tank install a system which complies with BS EN ISO 8099.
  • Boats complying with the inland waterways Boat Safety Scheme must have valve fitted to any overboard discharge lines.

Discharging into open water:


  • Only use sea toilets in open sea where waste will be quickly diluted and dispersed. Try to discharge more than 3 miles off the coastline.
  • Avoid discharging in areas of poor tidal flushing, such as marinas, or where there are shellfish beds.
  • Consider other water users and avoid discharging sewage in areas where there are other water users, such as bathing beaches.
  • Always give consideration to environmental sensitivity of the area before using your sea toilet. For example are you located in a protected area?


Boat Users


Green Products
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Related Resources

The Green Guide to
Outboard Efficiency

Stop The Spill
(Inland) Oil and Fuel

Stop The Spill
(Coastal) Oil and Fuel

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