Any responsible yacht owner should be sure their yacht is fitted with a black water tank for use when at anchor or close to shore. Black water (and in some countries grey water) should not be directly discharged into the sea within at least three miles of the coast.

MARPOL is the widely recognized abbreviation for the International Convention for the Prevention of Pollution from Ships, a convention adopted in 1973 by the International Maritime Organization (IMO) and modified for private pleasure vessels in 2018. Its primary goal is to prevent pollution of the marine environment by ships, both from operational and accidental causes.

While the MARPOL regulations do not apply to vessels under 400 tons (unless licensed to carry more than 15 passengers), pleasure yacht owners are advised to be aware of best practice, particularly regarding sewage (Annex IV) and garbage disposal (Annex V).

All vessels must comply with local regulations regarding pollution control (listed under the restrictions section in the country formalities pages).

It is worth noting that the Mediterranean is designated by MARPOL as a Special Area (certain areas of the ocean, designated as specifically vulnerable to pollution and needing increased protection) and according to Annex IV, no untreated sewage may be discharged, and Annex V, garbage disposal is strictly limited.

See a list of other Special Areas here.

The requirement for a ship to display placards which notify the crew and any passengers of the requirements for the disposal of garbage contained in regulations 26-28 (plastic disposal prohibited and general waste subject to limitations) and 30 (Antarctic waters), applies to all ships of 12m or more in overall length.

The basic rule for the Mediterranean is that all waste (including sewage) should be returned to land and disposed of properly. The only permitted discharge within 12 miles of the coast is of deck cleaning agents, provided they are not harmful to the marine environment.