Opinion piece: A call for realism and progress in legionella prevention

H2O Enterprise, HJ Klijnstra 

The recent developments regarding the adjustment of the Legionella standard offer opportunities, but also raise questions. The differentiation of the standard to only act when Legionella pneumophila is detected seems at first sight to be a step forward, certainly when we look at the effectiveness and proportionality of the measures. Nevertheless, it is important to warn against excluding Legionella non-pneumophila from the mandatory sampling. After all, these bacteria function as valuable indicators for the condition of the tap water installation and can provide crucial insights into the presence of risks.

Non-pneumophila: a missed opportunity for prevention

The discussion is not only about simplifying the standard, but also about maintaining insight into the general bacteriological condition of drinking water installations. Legionella non-pneumophila, although less pathogenic than Legionella pneumophila, has an important function in prevention. The occurrence of this group of bacteria can indicate optimal conditions within the installation. A finding of Legionella non-pneumophila functions as an indicator of shortcomings within the drinking water installation or inadequate management. Think of stagnation, biofilm formation or temperature deviations. The complete exclusion of Legionella non-pneumophila from the monitoring can therefore lead to a repressive approach, in which action is only taken when Legionella pneumophila is found above the standard.

The detection of Legionella non-pneumophila works as an early warning system. It helps to proactively manage maintenance and management of installations, which is essential for stable and safe drinking water quality. By eliminating non-pneumophila from the control, we risk blind spots in our preventive strategy.

The <100 cfu/l standard non-pneumophila: an expensive burden without measurable benefit

The current threshold value of <100 colony-forming units per litre (cfu/l) for Legionella non-pneumophila is unrealistically strict in the Netherlands and entails unnecessary costs. In neighbouring countries, such as Germany and Belgium, a standard of <1,000 cfu/l is used, a value that is both scientifically and practically substantiated. We advocate that the Netherlands follows this line.

The high costs that are now incurred for minimal exceedances of up to 1,000 cfu/l are not in proportion to the risks to public health. A realistic increase to <1,000 cfu/l would ensure more efficient management and cost savings, without compromising safety. It is important that we continue to invest in sustainable solutions that make a structural difference, instead of reacting to minimal fluctuations.

A policy that only requires Legionella pneumophila sampling puts owners of collective water systems on a reactive track. There is a risk that managers will only take measures after the standard for Legionella pneumophila has been exceeded, while non-pneumophila could have warned us earlier.

Progress with an eye for proportionality

H2O Enterprise strongly supports progress in legionella prevention. The focus on Legionella pneumophila is an important step, but should not be at the expense of insight into the general bacteriological status of installations. The discussion about <100 cfu/l versus <1,000 cfu/l requires realism and balance.

By raising the standard, we can keep legionella prevention affordable and create space for investments in innovation. Think of new detection methods, improved installation designs and sustainable solutions that tackle risks structurally. By deploying our resources more effectively, we will arrive at a legionella policy that is not only proportionate, but also future-proof.

Conclusion: let us learn from our neighbouring countries

The Netherlands has a unique opportunity to realize future-proof legionella prevention. A focus solely on Legionella pneumophila is valuable, but should not be at the expense of the insight that Legionella non-pneumophila offers into the overall condition of tap water installations. Completely excluding these bacteria from monitoring is a step too far and risks the effectiveness of our preventive measures.

By not excluding non-pneumophila bacteria and increasing the threshold to <1,000 cfu/l, we kill two birds with one stone: we retain valuable insights and make legionella prevention more effective. It is time to focus the debate on proportionality, realism and innovation, so that we actually make progress in the management of our tap water installations.

Together we can work on policies that balance public health, sustainability and cost savings.