- Black water – Drainage from toilets. Black water has a high biological oxygen demand and can increase other nutrients in the water, and also can have the potential to introduce disease.
- Galley water – Galley water can contain oil, fats and detergents – all of which have a detrimental effect on marine life.
- Grey water – Drainage from dishwater, showers, laundry, bath and washbasin drains and does not include drainage from toilets, urinals, hospitals and cargo spaces. Each person can produce between 170 and 350 litres of grey water a day. Grey water contains soap, dental waste, antiseptics, disinfectants, deodorants and other substances.