Life aboard a ship produces certain residual liquids, such as wastewater. Sewage or “black” waters are wastewater from sanitary toilets / urinals. “Grey’’ waters are wash water (sinks, showers, washing machine, dishwasher, etc.).
Discharge of untreated black water causes bacterial pollution from pathogens that can be harmful for human health and aquatic wildlife.
The discharge of grey water can enhance algae growth (due to the supply of an excessive amount of nutrients), clog fishs’ gills (from fat), and cause suffocation of small species by suspended particulate matter.
In Canada, these discharges are strictly regulated, in accordance with MARPOL requirements. Ships navigating in Canadian waters are inspected on a regular basis to make sure they comply with regulations.
- Black water :
- Regulations require a ship that has a toilet on board to have a holding tank or an approved marine sanitation device.
- With some exceptions, the discharge of untreated sewage into all Canadian inland waters and Canadian coastal waters within 3 nautical miles of land (ships less than 400 tons) and 12 miles of land (ships larger than 400 tons) is banned.
- Discharge within these limits is only permitted after proper treatment (comminuted and disinfected) using a marine sanitation device.
- Any discharge in the Saint-Lawrence and the Great Lakes is prohibited without proper treatment, regardless of the distance from the shore.
- Treated sewage may be discharged into Canadian waters only if they are subject to specified limits of faecal coliforms per 100 ml of water.
- Grey water:
- Grey waters discharged into Canadian waters (other than Arctic waters, which are subject to other standards) must not result in the deposit of solids or cause any sheen on the water.
- Any discharge from a new passenger ship carrying more than 500 passengers, must always be made at a minimal distance of 3 nautical miles from shore and only after treatment using a marine sanitation device.