The warm, bubbling water of a hotel hot tub is often seen as a luxury, but these shared, enclosed water systems require consistent and scrupulous maintenance for safety. The elevated temperature and shared nature of the water provide an ideal habitat for certain microbes. Proper sanitation is the single most important factor determining guest safety, and understanding the actual risks allows you to make informed decisions before use.
Common Infections Associated with Hot Tubs
The warm environment of a hot tub is particularly conducive to the growth of specific bacteria and parasites that can cause illness. One of the most common issues is Folliculitis, often referred to as “hot tub rash,” which is caused by the bacteria Pseudomonas aeruginosa. This skin infection manifests as an itchy, bumpy, red rash, sometimes with pus-filled blisters, appearing a few hours to a few days after exposure. The bacteria thrives in the warm water, particularly in areas where swimwear traps contaminated water against the skin. Although Folliculitis is generally a mild infection that clears up on its own, it signals that the tub’s disinfectant levels are inadequate.
A serious risk comes from Legionella pneumophila, the bacteria responsible for Legionnaires’ disease, a severe form of pneumonia, and the milder Pontiac fever. Infection occurs when a user inhales tiny droplets of contaminated water, or aerosols, created by the hot tub’s jets and bubbles. Since hot tubs are often operated within the bacteria’s ideal growth range of 77–113°F, they are a frequent source of outbreaks when maintenance fails.
Another concern is the parasite Cryptosporidium, which is difficult to eliminate and is a leading cause of waterborne disease outbreaks in treated recreational water. Cryptosporidium causes diarrheal illness and can survive for days even in properly chlorinated water. The parasite spreads when water is swallowed, making it a risk especially for young children. These three organisms—Pseudomonas, Legionella, and Cryptosporidium—are responsible for the vast majority of water-related outbreaks associated with hotel hot tubs.
Critical Factors in Hot Tub Maintenance
The primary defense against these pathogens is the sanitation system, which relies on maintaining correct levels of disinfectant, such as chlorine or bromine. However, the effectiveness of these chemicals is entirely dependent on the water’s pH level. When the pH is too high (above 7.8), the chemical structure of the disinfectant changes, dramatically reducing its ability to kill germs, even if the concentration level appears correct.
The second major maintenance factor is the prevention of biofilm, a slimy layer of microorganisms that adheres to surfaces inside the hot tub’s plumbing, filters, and shell. This biofilm acts as a protective shield, allowing Legionella and Pseudomonas to hide from disinfectants. High water temperatures and heavy use by multiple guests quickly deplete the available disinfectant, making biofilm formation more likely.
The extreme chlorine tolerance of Cryptosporidium requires an additional level of sanitation beyond standard daily maintenance. When contamination is suspected, the Centers for Disease Control and Prevention (CDC) recommends a process called “hyperchlorination,” which involves elevating the chlorine level far above normal for an extended period. Many public spas are also now required to use secondary disinfection systems, such as ultraviolet (UV) light or ozone, because these technologies can inactivate chlorine-resistant organisms. Regulatory oversight and inspection frequency vary by locality, but adherence to guidelines like the CDC’s Model Aquatic Health Code is the industry standard for minimizing risk.
Pre-Use Safety Checks for Guests
Guests can perform a few simple checks to assess a hot tub’s maintenance before entering the water. The first is the “smell test”: a strong chemical smell does not indicate a clean tub but rather a problem. That odor is caused by chloramines, which are used-up disinfectant molecules combined with organic matter like sweat, urine, and oils.
The recommended maximum temperature for a healthy adult is 104°F (40°C); if the temperature feels significantly hotter, avoid entering. If the hotel posts inspection reports, a quick review can give insight into the tub’s maintenance history. If any of these checks raise concerns, report the issue to hotel management and avoid use until the problem is corrected.
Visual and Physical Checks
- The water should appear clear, not cloudy, murky, or foamy, which suggests poor filtration or inadequate sanitizer levels.
- Physically check the surfaces below the waterline for any sliminess or slickness, which is evidence of biofilm formation.
- Confirm that all jets and drains are functioning properly.
- Check the posted temperature, if available.
Medical Conditions Requiring Avoidance
For certain individuals, the inherent risks of hot tub use are magnified. Pregnant individuals should avoid hot tubs entirely or limit their soak to less than ten minutes at a temperature below 100°F (37.8°C). A rise in the mother’s core body temperature above 102.2°F (39°C) is linked to an increased risk of neural tube defects in the developing fetus, especially during the first trimester.
Individuals with heart conditions or high blood pressure should exercise caution, as the heat causes blood vessels to dilate, placing increased stress on the cardiovascular system. Anyone with open wounds, fresh piercings, or recent tattoos should stay out of the water, as any break in the skin barrier provides an easy entry point for bacteria like Pseudomonas. Individuals who are immunocompromised, such as those with diabetes, undergoing chemotherapy, or taking certain medications, are more susceptible to severe illness from waterborne pathogens.
Young children are at risk for rapid overheating because their bodies cannot regulate temperature as efficiently as adults. The CDC advises that children under five years old should not use hot tubs, and older children should limit their time to five to ten minutes with the temperature lowered below 100°F. Always exit the hot tub immediately if you feel dizzy, nauseous, or too warm.