Preventing legionnaires' disease

Do you own a building? You are responsible for the quality of its tap water. This means you also have to prevent Legionella from growing in your building’s pipes. You must take preventative measures, and take action when unhealthy amounts are detected. 

What is Legionella? 

Legionella is a bacterium that can cause an infection of the airways called legionellosis which may develop into legionnaires’ disease. Legionella bacteria may grow in water with a temperature between 20 and 55 degrees Celsius. For example: 

• tap water
• swimming pools 
• fountains and sprinkler water at garden centres and car washes
• cooling water in wet cooling towers 

People can catch legionnaires' disease by breathing in the bacteria through water droplets (mist) in the air. 

High-risk locations for Legionella 

Strict prevention rules apply for some businesses and institutions where the risk of infection with legionnaires’ disease is higher. These priority institutions (in Dutch) include: 

• hospitals and healthcare institutions (care homes, mental health centres, specialised care)
• swimming pools and establishments with pools on their premises, such as wellness centres and sex clubs
• saunas 
• hotels, B&B's, and holiday rental apartments that accommodate more than 5 guests
• asylum seekers' centres
• prisons
• locations with public showers, such as camping grounds, marina’s, and truck stops. 

Mandatory measures against Legionella 

Do you have such high-risk location? Then you must take measures to prevent infection (in Dutch). 

Have a mandatory risk analysis carried out by a professional 

You must ask a company with BRL 6010 certification to conduct a risk analysis (in Dutch). This analysis identifies where in your business or institution Legionella bacteria are growing or may start to grow. 

Draw up a Legionella management plan 

Based on the risk analysis, you must ask a BRL 6010 certified company to draw up a Legionella management plan. This sets out the measures you must take to prevent the growth of Legionella bacteria. It also details who is at risk of infection, and when there is extra risk of infection. 

You must take steps to prevent the (further) growth of Legionella bacteria, such as regularly flushing the pipes in your building. 

Keep a logbook 

You must also keep a logbook in which you record which measures you have taken, and when. 

Have your water checked twice a year 

You must have your water checked at least twice a year by a certified sampler. They will test the amount of colony-forming units of the bacteria per litre (cfu/l) in your tap water. 

Report unsafe Legionella levels 

Are you required to have your water checked? 

• Between 0 and 100 cfu/l, you have to do nothing. 
• Between 100 and 1000 cfu/l, you must take the measures described in your Legionella management plan to prevent further growth.
• If the result is over 1000 cfu/l, it is considered unsafe and you must report this within 48 hours. 

You report unsafe Legionella levels to the Human Environment and Transport Inspectorate (Inspectie Leefomgeving en Transport, ILT, in Dutch). You must take the measures described in your Legionella management plan, and take a retest until the number of bacteria is within safe levels. You record wich measures you have taken and when in your logbook. The ILT may inspect your building and your logbook following a report. 

Wet cooling towers 

If you use a wet cooling tower (in Dutch) to cool your building or manufacturing process, you must notify your municipality via the Environment and Planning Portal (in Dutch). Wet cooling towers release droplets of water into the air, which increases the risk of spreading Legionella bacteria.