Travel and Hospitality
Hotels, resorts and cruise ships account for a large share of identified Legionnaires’ disease outbreaks. Not because they are careless, but because they combine every condition the bacterium needs — and because their guests leave before anyone knows they are ill.
Warmth and time
Legionella needs two things to multiply: water held somewhere between roughly 77°F and 113°F, and time sitting undisturbed.
A hotel supplies both, continuously, as a consequence of operating normally.
Water is kept hot for guests around the clock. Pipe runs are long, because the building is large. And occupancy is uneven — a floor closed for the season, a wing at 40% in February, a room nobody has booked for three weeks. Every one of those is water standing still at a comfortable temperature.
None of that is a failure. It is what a hotel is. Which is why prevention in hospitality has to be deliberate rather than incidental.
Where exposure happens on the premises
Hot tubs and spa pools. The most consistently implicated source in the sector. They are held at temperatures ideal for bacterial growth, agitated in a way that produces exactly the fine aerosol that carries Legionella into the lungs, and carry a heavy organic load from bathers that consumes disinfectant. A spa pool needs its chemistry checked far more often than a swimming pool, and the interval is measured in hours rather than days.
Guest rooms between bookings. The distinctive hospitality risk, and the one most often overlooked. A shower that has not run for two weeks is a column of warm, still water. When the next guest turns it on, whatever grew in it aerosolises immediately, in a small enclosed room, at head height.
Decorative fountains and water features. Lobby installations are designed to move water through air, which is also a description of how Legionella reaches people. Indoor fountains have been linked to outbreaks repeatedly.
Seasonal reopening. A property closed for a season, or a wing shut for refurbishment, holds stagnant water throughout. Reopening without flushing is one of the highest-risk moments in the sector.
Cooling towers. Larger properties have them, and their mist can reach guests, staff and people who never entered the building.
Cruise ships. Whirlpool spas and potable water systems on vessels carry the same risks in a more concentrated setting, with passengers dispersing to many countries afterward
What the numbers show
CDC examined outbreaks associated with treated recreational water — pools, hot tubs and water playgrounds — reported between 2015 and 2019. There were 208 of them, causing at least 3,646 illnesses, 286 hospitalisations and 13 deaths.
A third of those outbreaks were associated with a hotel, motel or resort. Half began between June and August.
Among the outbreaks with a confirmed cause, Cryptosporidium was responsible for more of them than Legionella. Every one of the thirteen deaths occurred in a Legionnaires’ disease outbreak.
Source: Hlavsa MC, Aluko SK, Miller AD, et al. MMWR 70(20), 2021: 733–738. (free)
Having a programme is not the same as having a working one
Investigations in Crete published in 2025 and 2026 documented travel-associated Legionnaires’ disease cases linked to the same hotel across 2016 to 2018, and again from 2023 to 2025 — despite surveillance and control measures being in place throughout.
That is worth sitting with. This was not a property that had never considered the problem. It was a property under active surveillance, with measures in place, producing cases across nine years.
It matches what CDC found when it reviewed its own outbreak investigations: in 40% of cases the building had a water management programme that was adequate on paper and was not being followed.
A programme that exists but does not work is its own category of failure, and it is not detectable from the outside by anyone.
What prevention looks like here
The controls are not unusual. What is unusual is the discipline hospitality requires to keep them running through seasonal swings, staff turnover and variable occupancy.
A written water management programme covering the whole property — potable water, spa pools, fountains, cooling towers, ice machines — following ASHRAE Standard 188.
Flushing protocols for low-occupancy rooms. A defined interval, a defined duration, a record that it happened. This is the single most sector-specific control, and the easiest to let slide when a property is quiet.
Spa pool discipline. Frequent chemistry checks, documented, with defined action when a reading falls outside limits. Not a daily glance at a test strip.
A reopening procedure after any closure, seasonal or otherwise, carried out before guests return rather than as they arrive.
Testing that produces records somebody reviews.
A named individual responsible — not a department, not a role. In an industry with high staff turnover, a programme assigned to a job title is a programme that ends quietly when someone leaves.
If you are travelling
You cannot inspect a building’s plumbing, and it is not your job to. But a few things are worth knowing.
Run the shower before you use it. Two or three minutes on hot, with the bathroom door open and yourself out of the room, clears water that has been standing in the line. This is the single most useful thing a guest can do, and it costs nothing.
Be cautious with hot tubs if you are over 50, smoke or used to smoke, have a chronic lung condition, or have a weakened immune system. The risk is not the water itself but the aerosol above it.
If you become unwell within two weeks of a trip, tell your doctor where you have been. That exposure history is often the only reason the right test gets ordered.
Symptoms and what to ask a doctor →
Before your next stay
Ten questions you can put to a hotel, with what a good answer sounds like. It costs nothing to ask, and most properties are never asked.
Questions to ask your building manager — download (PDF) →
Prevention should not depend on which state a hotel is in
Most properties face no requirement to test their water or to tell anyone what they found. We work to change that.
Know when it happens near you
We send occasional alerts on outbreaks, legislation and new research. No more than that.
Sources
- CDC, About Legionnaires’ Disease — (free)
- Hlavsa MC, et al., Outbreaks Associated with Treated Recreational Water — United States, 2015–2019, MMWR 70(20), 2021 — (free)
- CDC, Key Findings: Outbreaks and Water Management Gaps — (free)
- Fitzhenry R, et al., Emerging Infectious Diseases 23(11), 2017 — travel-associated case proportion — (free)
- Travel-associated Legionnaires’ disease investigations, Crete, 2025–2026 — (free)
- New Jersey P.L. 2024, c.66 — (free)
- ASHRAE Standard 188 — (purchase required)