Guidance for Resumption of Cruise Operations After No-Sail Period or Reduced Operation

Minimize the growth and transmission of Legionella in cruise ship water systems and devices

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After prolonged no-sail period or reduced operation of cruise ships, stagnant water in ship water systems can increase the risk of Legionella growth and transmission when operations resume. Stagnant water can create favorable conditions for Legionella growth by

  • Reducing water temperatures to the Legionella growth range
  • Encouraging biofilm growth in areas of stagnation
  • Reducing disinfectant levels

Below are considerations for cruise ship operators prior to and during the resumption of cruise operations:

1. Water management program modifications and implementation

  1. Person writing on a clip board.

    If not already in place, develop and implement a comprehensive water management program (WMP) for ship water systems and all devices that use water.

  2. Perform a comprehensive review of the ship’s current WMP and determine which components may need modifications based on the ship’s operational status over recent months and planned changes in operations and occupancy as ships prepare to resume operations with reduced passenger capacity. These WMP modifications may need to reflect a lower water demand as operations resume with a reduced load of passengers and crew as well as account for cabins that are designated for isolation/quarantine purposes. These operational changes may lead to water pressure fluctuations, water stagnation, and increased water age in certain decks or parts of decks.
  3. Below are some considerations for cruise operators when reviewing WMPs for potable water systems:
    1. Identify specific decks or areas of decks where there may be potential for water stagnation or water pressure changes. These changes may impact water quality in other areas of the ship that are connected to those identified areas.
    2. Determine control measures to implement and establish a plan for how to monitor water quality parameters in those identified locations.
  4. Additional guidance on WMP development and implementation is available:

2. Potable water system

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  1. Consider contacting the local water utility at shore-side ports where potable water will be bunkered to learn about any recent water supply disruptions and confirm that routine checkpoints and disinfectant residuals have been recently inspected and meet expected standards (Reference 2018 Vessel Sanitation Program Operations Manual Sections and 5.2).
  2. For ships that have not been in use or have been in reduced operational status, or where water remained stagnant, consider cleaning and disinfection procedures followed by flushing of the potable water system, tanks, and associated system components prior to resuming or expanding operations. Please refer to 2018 Vessel Sanitation Program Operations Manual sections 5.3.4, 5.3.5, 11.2, and 13.6 for cleaning and disinfection methods. For flushing after cleaning and disinfection, please consider the following:
    1. Flush hot and cold water through all points of use throughout the ship (e.g., showers, sink faucets in cabins, salons, galley, recreational and technical areas) to replace water inside the piping with fresh potable water.
    2. Ensure that the hot water reaches its maximum temperature when flushing, with precautions for scalding in place.
  3. Consider how reduced occupancy may impact potable water tank storage and manage accordingly (e.g., rotation schedule of potable water tanks).
  4. Develop and implement flushing procedures to mitigate risk and maintain water quality associated with changes in occupancy during operations.

3. Decorative water features and other devices

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  1. Adhere to manufacturer guidelines and recommendations for cleaning, operation, and maintenance of decorative water features and other devices (e.g., misting systems, salon/pedicure devices) (Reference 2018 Vessel Sanitation Program Operations Manual section 11.2).
  2. Ensure decorative water features and other devices are free from visible biofilm or slime.
  3. After water features are refilled and running, confirm that the disinfectant treatment system is operating according to specifications.

4. Recreational water facilities

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  1. Adhere to 2018 Vessel Sanitation Program Operations Manualpdf icon guidelines for cleaning, operation, and maintenance procedures (Reference 2018 VSP Operations Manual section 6.0).
  2. Ensure recreational water facilities (RWFs) are free from visible biofilm or slime.
  3. Prior to RWFs returning to service, perform an inspection for any repairs that may be needed.
  4. If RWFs were not properly drained and cleaned prior to the no-sail period and water remained stagnant, cruise operators should consider following a cleaning and disinfection procedure similar to the solid fecal accident response plan (Reference 2018 VSP Operations Manual Section 13.9). This includes procedures such as inspection and backwash of filters and disinfection prior to resuming operations.

5. Special considerations for public and in-cabin private whirlpool spas

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  1. Follow CDC cleaning and disinfection procedures for whirlpool spas (WPS)pdf icon (please note that in this guidance document, WPS are also referred to as hot tubs).
  2. Follow CDC remediation procedures (Steps 4–9 and 12–13) for WPS not properly drained and cleaned prior to or during the no-sail period, or if there are gaps and concerns in the maintenance records, such as the following:
    1. Missing or incomplete record of when spas were last drained and cleaned prior to suspension of operations
    2. Halogen levels persistently below target levels
    3. Disruption in the pH and disinfectant monitoring or automatic feeder system
  3. Ensure that private WPS in individual cabins, as well as their system components, are thoroughly cleaned and disinfected prior to resuming sail (Reference VSP Manual Section 6.6).

6. Technical water systems

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  1. Legionella bacteria have been recovered from technical water sources. Perform an environmental assessment of the locations where technical water is utilized throughout the ship and determine whether there is a risk of aerosolization exposure to crew and passengers.
  2. If the potential for Legionella growth is suspected in technical water sources, or if the risk of exposure to Legionella in technical water sources cannot be mitigated, consider the following:
    1. Use of administrative control to prohibit exposure of passengers to technical water aerosols (e.g., deck washing with technical water in the absence of passengers)
    2. Use of personal protective equipment (PPE) among crew, such as a half-face air-purifying respirator equipped with an N95 filter. These respirators must be used in accordance with a comprehensive respiratory protection program, which includes fit testing, training, and medical clearance ahead of their use (see OSHA standard 29 CFR 1910.134external icon).

7. Validation of the WMP using Legionella testing

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  1. Before resuming or expanding operations, cruise operators should consider testing ship water systems for Legionella to validate the efficacy of the implemented WMP and confirm the absence of Legionella (if laboratory testing is available and feasible at the time).
  2. Cruise operators may decide to test public or private WPS for Legionella before returning to service if they were not properly drained and cleaned prior to or during the no-sail period or if there are gaps and concerns in the maintenance records. Please refer to section 5b for examples of maintenance concerns.
  3. The WMP team should base decisions about routine environmental sampling for Legionella on a variety of factors, including findings from an environmental assessment and water quality data supporting the overall performance of the WMP.
  4. According to ASHRAE Standard 188-2018external icon, when routine environmental Legionella testing is pursued, it should be conducted by a laboratory that is accredited by a regional, national, or international accrediting body according to a nationally or internationally recognized standard, such as ISO/IEC 17025. Cruise operators should ensure that the chosen method of testing for Legionella is included in the laboratory’s scope of accreditation. Please note that laboratories meeting this designation may not necessarily be members of the Environmental Legionella Isolation Techniques Evaluation (ELITE) Program.

8. Clinical surveillance

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  1. Provide the following reminders to the medical/clinical staff regarding Legionnaires’ disease and Legionella testing:
    1. Signs and symptoms of Legionnaires’ disease can be similar to other respiratory illnesses and include fever, cough, and shortness of breath. Pneumonia caused by Legionella may be indistinguishable radiographically from pneumonia caused by other pathogens.
    2. Co-infection with other respiratory pathogens is possible.
    3. Ship medical staff are uniquely positioned to help identify and diagnose cases of Legionnaires’ disease among travelers.
    4. Legionnaires’ disease is treatable with antibiotics (macrolides or fluoroquinolones).
    5. Passengers or crew members with clinical or radiographical evidence of pneumonia should be tested for Legionnaires’ disease via urinary antigen test.
    6. Additional guidance for clinicians about Legionnaires’ diseasepdf icon is available
  2. Report cases of Legionnaires’ disease to the CDC Legionella Program at