Resuming Cruise Operations

Guidance for Use After a No-Sail Period or Reduced Operation

Key points

  • Cruise ship operators should take steps to minimize Legionella growth and transmission in water systems and devices.
  • This guidance addresses special considerations prior to and during the resumption of cruise operations after a no-sail period or reduced operation.
Illustrations representing a cruise ship and hot tub

The problem

A prolonged no-sail period or reduced operation of cruise ships can result in stagnant water in ship water systems. This stagnant water 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


Cruise ship operators: Detailed below are 8 areas of consideration prior to and during the resumption of cruise operations.

  1. Water management program modifications and implementation
  2. Potable water system
  3. Decorative water features and other devices
  4. Recreational water facilities
  5. Public and in-cabin private whirlpool spas
  6. Technical water systems
  7. Validation using Legionella testing
  8. Clinical surveillance

1. Water management program modifications and implementation

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

Comprehensive review

Perform a comprehensive review of the ship's current WMP.

Determine which components may need modifications based on the ship's

  • Operational status over recent months
  • Planned changes in operations and occupancy as ships resume operations

WMP modifications may need to reflect a lower water demand due to a reduced load of passengers and crew. They also may need to account for cabins that are designated for isolation/quarantine purposes. These operational changes may lead to

  • Water pressure fluctuations
  • Water stagnation
  • Increased water age in certain decks or parts of decks

Considerations for potable water systems

Identify specific decks or areas of decks where there may be potential for

  • Water stagnation
  • Water pressure changes

These changes may impact water quality in other areas of the ship that are connected to those identified areas.

Determine control measures to implement. Establish a plan for how to monitor water quality parameters in those identified locations.

CDC trainings available‎

CDC and partners offer a comprehensive training on creating a water management program to reduce risk for Legionnaires' disease. The PreventLD training aligns with industry standards (ASHRAE 188) on managing risk for Legionella bacteria.

2. Potable water system

Consider contacting the local water utility at shore-side ports where potable water will be bunkered. Discuss any recent water supply disruptions. Confirm that routine checkpoints and disinfectant residuals have been recently inspected and meet expected standardsA.

Cleaning and disinfection procedures

Cruise operators should consider cleaning and disinfection procedures if shipsB:

  • Haven't been in use
  • Have been in reduced operational status
  • Have water that has remained stagnant

Flushing procedures

Flush the potable water system, tanks, and associated components prior to resuming or expanding operations. This replaces water inside the piping with fresh potable water.

Flush hot and cold water through all points of use throughout the ship, which include but aren't limited to:

  • Galley
  • Recreational areas
  • Salons
  • Showers in cabins
  • Sink faucets in cabins
  • Technical areas

Ensure that the hot water reaches its maximum temperature when flushing, with precautions for scalding in place.

Develop and implement flushing procedures to mitigate risk and maintain water quality associated with changes in occupancy during operations.

Water storage considerations

Consider how reduced occupancy may impact potable water storage and manage accordingly (e.g., rotation schedule of potable water tanks).

3. Decorative water features and other devices

Adhere to guidelines and recommendations from the manufacturer for cleaning, operation, and maintenance of decorative water features and other devicesC:

  • Misting systems
  • Salon/pedicure devices

Ensure decorative water features and other devices are free from visible biofilm or slime.

After water features are refilled and running, confirm that the disinfectant treatment system is operating according to specifications.

4. Recreational water facilities

Adhere to guidelines for cleaning, operation, and maintenance proceduresD.

Ensure recreational water facilities (RWFs) are free from visible biofilm or slime.

Prior to RWFs returning to service, inspect for needed repairs.

Special considerations

Consider following a cleaning and disinfection procedure similar to the solid fecal accident responseE plan if

  • RWFs weren't properly drained and cleaned prior to the no-sail period
  • Water remained stagnant in RWFs

This includes procedures such as inspection and backwash of filters and disinfection prior to resuming operations.

5. Public and in-cabin private whirlpool spas

Follow CDC guidance for cleaning and disinfecting whirlpool spas. Note whirlpool spas are sometimes referred to as hot tubs.

Ensure that private whirlpool spas in individual cabins are thoroughly cleaned and disinfected prior to resuming sailF. This includes their system components.


Follow CDC remediation proceduresG for whirlpool spas not properly drained and cleaned prior to or during the no-sail period.

Maintenance records concerns

Use the same remediation procedures if there are gaps and concerns in the maintenance records, such as:

  • Missing or incomplete records prior to suspension of operations
    • Examples: Last drainage and cleaning records
  • Halogen levels persistently below target levels
  • Disruptions in pH/disinfectant monitoring or automatic feeder system

6. Technical water systems

Legionella bacteria have been recovered from technical water sources.

Perform an environmental assessment of the locations where technical water is used throughout the ship. Determine whether there is a risk of aerosolization exposure to crew and passengers.

Consider the following for any technical water sources where potential for growth is suspected or exposure that can't be mitigated:

Administrative controls

Prohibit exposure of passengers to technical water aerosols (e.g., deck washing with technical water in the absence of passengers).

Personal protective equipment

Use of personal protective equipment (PPE) among crew. This could include a half-face air-purifying respirator equipped with an N95 filter.

These respirators must be used in accordance with a comprehensive respiratory protection programH. Prior to use, these respirators require

  • Fit testing
  • Medical clearance
  • Training

7. Validation using Legionella testing

Benefits of testing

Before resuming or expanding operations, cruise operators should consider testing ship water systems for Legionella toI

  • Validate the efficacy of the implemented WMP
  • Confirm the absence of Legionella

Other considerations

The WMP team should base decisions about routine environmental sampling for Legionella on a variety of factors, including:

  • Environmental assessment findings
  • Water quality data

Testing whirlpool spas: Considerations‎

Cruise operators may decide to test public or private whirlpool spas for Legionella before returning to service. This is important if they weren't properly drained and cleaned or if there are maintenance records concerns as discussed above.

Selecting a testing laboratory

Adhere to ASHRAE Standard 188 by selecting an accredited laboratory when routine environmental Legionella testing is pursued. The selected regional, national, or international accrediting body should follow 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.

Laboratories meeting this designation may not necessarily be members of the Environmental Legionella Isolation Techniques Evaluation (ELITE) Program.

8. Clinical surveillance

Provide reminders to the medical/clinical staff regarding Legionnaires' disease and Legionella testing on the following topics:

Signs and symptoms

Signs and symptoms of Legionnaires' disease can be similar to other respiratory illnesses. They include:

  • Cough
  • Fever
  • Shortness of breath

Pneumonia caused by Legionella may be indistinguishable radiographically from pneumonia caused by other pathogens.


Co-infection with other respiratory pathogens is possible.

Role of medical staff

Ship medical staff are uniquely positioned to help identify and diagnose cases of Legionnaires' disease among travelers.


Legionnaires' disease is treatable with antibiotics (macrolides or fluoroquinolones).

Need for testing

Passengers or crew members with clinical or radiographical evidence of pneumonia should be tested for Legionnaires' disease via urinary antigen test.

Case reporting

Report cases of Legionnaires' disease to the CDC Legionella Program at

What medical staff need to know about Legionnaires' disease‎

CDC has resources designed for medical staff about Legionnaires' disease.
  1. Reference 2018 Vessel Sanitation Program Operations Manual Sections and 5.2.
  2. Reference 2018 Vessel Sanitation Program Operations Manual sections 5.3.4, 5.3.5, 11.2, and 13.6.
  3. Reference 2018 Vessel Sanitation Program Operations Manual section 11.2.
  4. Reference 2018 VSP Operations Manual section 6.0.
  5. Reference 2018 VSP Operations Manual Section 13.9.
  6. Reference VSP Manual Section 6.6.
  7. Reference steps 4–9 and 12–13.
  8. Reference OSHA standard 29 CFR 1910.134.
  9. Testing depends on if laboratory testing is available and feasible at the time.