Introduction:
During the ship's stay in port, an inspection may be required to verify the compliance with WHO standards for health and hygiene and to issue the Ship Sanitation Certificate. The inspections are based on Annex 3 of the International Health Regulations and the World Health Organization recommendations^1-3. All ships must implement a Potable Water Quality Monitoring Plan3, to ensure that the potable water supply system on the ship is operating safely, as well as to control the level of sanitation of the entire internal system. When requested, the Border Health Service of the Port of Leixões, through Environmental Health Team (EHT), collects water samples to test for physical-chemical and microbiological parameters.

Methods:
This study aims to describe the results obtained from the water monitoring plan on ships, resulting from samples collected by the Port of Leixões Health Authority. From February 2022 to May 2024, our EHT analysed the presence of Legionella (pneumophila and non- pneumophila spp.), free chlorine concentration and pH, microorganisms at 36ºC and 22ºC, coliform bacteria, E. coli, Enterococci, C. perfringens, and the presence of heavy metals.

Results:
From February 2022 to May 2024, 100 water samples were taken from 11 cargo ships. Of these, 63 were analyzed for Legionella pneumophila and non-pneumophila spp., detecting Legionella pneumophila at 14 points and Legionella spp. at 16. For free chlorine (n=95), 56 points showed values below 0.2 ppm. Among microbiological samples, 4 had "microorganisms at 36ºC" and "microorganisms at 22ºC" above recommended values, and 2 had coliforms above the parametric value. For chemical parameters (n=37), 7 had iron, 4 had lead, and 1 had cadmium above the parametric values.

Conclusion:
Ships must maintain water quality monitoring to assess the risk of microbiological and chemical contaminants. It is essential that the water supplied to the ship is of high quality and that a water safety plan is implemented.