Regulations on environmental health care require risk assessments to be carried out for facilities that directly or indirectly can spread Legionella via aerosol to the surroundings. Ship owners, operators and managers are jointly responsible.
IMO/WHO Guide to Sanitation, third edition 2011 says (excerpts):
…… The ship’s master or officer responsible for bunkering water must be responsible for ascertaining whether or not the source of the water is potable. All staff should be encouraged to report symptoms indicating a potential waterborne disease. The ship’s operator needs to provide adequate toilet and washing facilities for the crew to maintain personal hygiene. Known carriers of communicable diseases should never come into contact with potable water supplies. An adequate ratio of crew to facilities is required on board ship to enable proper servicing and maintenance activities.
…… Minimum requirements can be found in ILO Convention C133 and the Maritime Labour Convention, 2006. The term “fresh water” used in ILO conventions and the Maritime Labour Convention, 2006 should be interpreted as meaning potable water. To reduce disease spread among crew, shared drinking receptacles should not be used on ships unless they are sanitized between uses.
…… The potable hot-water system, including showerheads, shall be maintained to minimize the growth of pathogenic Mycobacterium or Legionella bacteria. Showerheads should be cleaned and disinfected every six months. Aerators may harbour very high numbers of pathogenic bacteria such as Pseudomonas aeruginosa. Therefore, the aerators should be regularly cleaned and disinfected.
…… Furthermore, parasites such as Cryptosporidium produce oocysts that are very resistant to chlorine or chloramine disinfection and need to be removed by filtration or inactivated by an alternative method, such as UV irradiation.
…… In extended distribution systems, a residual disinfectant should be maintained to limit the growth of microbial hazards that can impart off flavours to the water and foul lines and fittings. Maintaining residual disinfection will contribute to the control of Legionella spp., for instance. In addition, this residual may kill very low levels of some pathogens that may gain entry to the network.