Sewage wastes (also called black water) are produced for most part from land-based resources such as municipal sewers or treatment facilities, and to a lesser extent by ships. Sewage and grey water 1 are generated by all vessels and may end up at sea either in treated or untreated form; sewage may also be retained 108aboard until it is discharged ashore to reception facilities. Due to their composition, uncontrolled sewage discharges at sea, especially near the coasts, may impair public health and ecosystems. According to scientists, pollutants such as metals, endocrine disrupters or pathogens may be present in sewage discharges. 2 In this context, a number of adverse phenomena have been associated with sewage, including, for example, oxygen depletion. The adverse aesthetic impact of sewage waste at sea can also be considered an issue.