World Health Organization Guidelines – “Source water is monitored at the port to ensure that water is safe. The ship’s master is responsible for operational monitoring: quality of source water: disinfectant residuals and pH (e.g., daily); microbial quality of treated water, particularly after maintenance or repairs. The frequency of monitoring should reflect the probable rate of change in water quality. For example, monitoring of drinking-water on ships may be more frequent when the ship is new or recently commissioned, with frequencies decreasing in the light of review of results. Similarly, if the ship’s water system has been out of control, monitoring following restoration of the system would be more frequent until it is verified that the system is clearly under control.”