Legionella – what it is and why you should care

Legionella is a type of bacteria that loves warm water. When you breathe in tiny droplets that contain the bug, it can cause Legionnaires' disease – a serious lung infection. Most healthy people handle a small exposure without trouble, but older adults, smokers, and those with weak immune systems can get very sick. The good news is that simple habits can keep the bacteria away from your tap, shower, and vacation stays.

Where Legionella hides

The bacteria thrives in water that sits between 20 °C and 50 °C (68 °F‑122 °F). That means hot tubs, decorative fountains, cooling towers, and even the pipes under your sink are prime spots. Stagnant water is a bigger problem than running water, so anything that isn’t used for weeks can become a breeding ground. Hotels, hospitals, and large office buildings often have complex water systems, making them common places for outbreaks.

Legionella also lives in older plumbing that has rust or scale buildup. The rough surfaces give the bacteria a place to cling and multiply. If you’ve ever had a shower that sputters or a faucet that drips, those tiny imperfections might be a silent home for the bug.

Simple steps to keep Legionella out

1. Flush unused water sources. Run the tap for at least 30 seconds after a vacation or a long weekend, especially in showers and bathtub faucets. This pushes fresh water through the pipes and clears out any settled bacteria.

2. Maintain hot water temperature. Set your water heater to at least 60 °C (140 °F). The heat kills Legionella, but remember to mix hot water with cold at the tap to avoid scalds.

3. Clean and disinfect. Regularly scrub showerheads, faucet aerators, and any removable parts. Soak them in a diluted bleach solution (one tablespoon of bleach per gallon of water) for 10‑15 minutes, then rinse.

4. Check hot tubs and pools. Test chlorine or other disinfectant levels weekly, and keep the water circulating. Stagnant hot tubs are a fast lane for Legionella.

5. Be cautious in public places. When staying in a hotel, ask about their water maintenance program. If the room has a shower that sputters or a faucet that drips, request a room change.

Following these habits cuts the chance of a Legionella infection dramatically. If you ever develop a fever, cough, or shortness of breath after a recent water‑related exposure, see a doctor right away and mention the possibility of Legionnaires' disease.

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