The European Water Framework Directive summarises 33 priority and 8 other contaminant substances. In accordance with the Integrated Water Policy decree, efforts must be made to reduce and/or eliminate discharges and emissions of these substances. Water analyses show that there have been virtually no further exceedences of the water quality standards for these 41 substances.
The content of certain fertiliser substances, primarily phosphates and nitrates, in the port harbours is significantly lower than in the Scheldt and Albert Canal watercourses, which provide the most important supply of water for the harbours on the left and right banks. The nitrogen concentration has decreased over the years, but the standard quality for total nitrogen concentration (summer half-year average < 1.8 mg N/l) has also not yet been achieved.
Oxygen can also cause a problem in the harbours, given that the standard quality of 30 mg O2/l is regularly exceeded for the chemical oxygen demand (COD). The COD is a dimension for the oxygen that is needed to decompose the organic material in the water column.