What Is Legionnaires’ Disease?

One key part of this is raising awareness of Legionnaires’ Disease—a rare but serious lung infection caused by Legionella bacteria. Although the risk is very low for most hot tub users, simple precautions can significantly reduce the chance of exposure.

What Is Legionnaires’ Disease? Legionnaires’ Disease is a severe form of pneumonia contracted by inhaling tiny droplets of water that contain Legionella bacteria. These bacteria naturally exist in water but thrive in warm, stagnant environments—especially where hygiene is poor.

Important: You cannot catch Legionnaires’ Disease from drinking water or from other people. Common Sources of Legionella

Legionella is typically linked to large or poorly maintained water systems, such as:

• Cooling towers and HVAC systems

• Hot and cold water systems in hotels, hospitals, and office blocks

• Unused taps or showers

• Decorative fountains, humidifiers, and misting systems

• Whirlpool baths in gyms or salons

Public facilities have a legal duty to manage these risks through professional maintenance and regular assessments.

Who Is Most at Risk? While anyone can get Legionnaires’ Disease, certain groups are more vulnerable:

• Adults over 45

• Smokers and heavy drinkers

• People with chronic illnesses (e.g. diabetes, asthma)

• Individuals with weakened immune systems

Recognising the Symptoms Symptoms usually appear within 2–14 days of exposure and resemble pneumonia:

• High fever and chills

• Persistent cough (with or without mucus)

• Muscle aches

• Confusion or mental changes

If symptoms follow hot tub use or exposure to any water system, seek immediate medical help and mention potential Legionella exposure. Early treatment with antibiotics like clarithromycin is essential.

Hot Tubs and Legionnaires’ Disease: What You Need to Know Hot tubs, like any warm water system that produces mist or spray, can harbor Legionella if not properly maintained. The good news? With regular care, the risk is extremely low.

To keep your hot tub safe:

• Use continuous disinfectant (e.g., chlorine or bromine) as per manufacturer guidance.

• Test the water before each use at home, and at least twice daily in business settings (every 2 hours in commercial spas).

• Log all test results and maintenance, keeping records for at least five years (for business/commercial use).

• Follow BISHTA Standards, and health and safety guidelines like HSG 282 (HSE) and PWTAG's resources for business settings.

Business operators should use commercial-grade spa systems designed for high bather loads and water turnover.

Prevention Starts with Good Practice Legionnaires’ Disease is extremely rare in well-maintained hot tubs. Whether at home or in a business setting, following proper water treatment protocols is the best way to stay safe. BISHTA urges all hot tub professionals to stay updated on current guidance and ensure staff are trained in Water Hygiene Management. Training is available through BISHTA.

Expert Help from BISHTA Members Every BISHTA member must have at least one staff member trained in Water Hygiene Management—many have several. This ensures customers receive reliable advice and safe water care practices. When you buy from or consult a BISHTA member, you get access to expert support. If you have questions about water testing, disinfectant use, or spa maintenance, your local BISHTA member is there to help.