Legionella – A Current Issue

Each year, the topic of legionella reappears in the media. Most recently, an SRF article was published. The increase in cases is alarming, and the Swiss Federal Office of Public Health (FOPH) has been alert for some time. In September 2021, there were also cases of Legionnaires’ disease in Argentina, which led to 4 deaths.

What Are Legionella?

Legionella are bacteria that are not always harmful and may naturally occur, even in drinking water. They are often discovered during a drinking water test. This test is now a legal requirement. In rental properties, it is the landlord's responsibility. Neglecting this duty can have serious consequences, particularly if tenants suffer health issues – even legal action may follow.

When Is a Water Test Result Considered Critical?

As mentioned, legionella can occur naturally and do not always pose a serious health risk. What matters is the quantity. If a test finds over 100 colony-forming units (CFU) per 100 ml, immediate action is required. Still, there is no need to panic. A small increase may be managed by taking hotter showers. Hot water is effective at suppressing the bacteria. At 70°C, legionella can be completely eliminated, and even temperatures above 60°C can reduce the bacteria significantly.

How Can Legionella Growth Be Prevented?

It’s important to understand that legionella cannot be 100% prevented. However, targeted measures can reduce the risk. As noted above, water analysis is key. In some cases, renovating the plumbing system may also be necessary and effective.

What Should Elderly or Immunocompromised Individuals Keep in Mind?

Older people and those with weakened immune systems should be especially careful. It's recommended to regularly use hot water at 60–70°C or to activate a “legionella program” on the boiler several times per month. Showers pose particular risk, as legionella can be transmitted through aerosols – tiny droplets invisible to the naked eye. A shower filter can help reduce risk. In severe cases, showering may need to be completely avoided.

Landlords and Property Managers Must Inform Tenants

If a water test detects a high legionella load, landlords or property managers must inform tenants via written notice or posting. Above a certain level, water usage and showering must be prohibited. In such cases, tenants may need to be temporarily relocated to a hotel.

Testing for Legionella

With our Legionella water test, your samples are examined in our accredited lab. This gives you clarity on whether your household is affected.