New tap water rules already flowing ahead of EU rubber stamp

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While waiting for the go-ahead to the overhauled Drinking Water Directive (DWD), some EU member states, as well as the UK, have already started implementing methods for microbiological analysis of water quality suggested in the new rules.

Once in force, the revisited directive will update parameters of water quality set more than 20 years ago, correcting shortcomings and dealing with materials in contact with drinking water as well.

Last December, EU lawmakers and member states agreed on which parameters could guarantee the highest possible level of health to restore citizens’ trust in tap water, clinching an informal deal on a crucial environmental and health dossier.

However, a formal approval of the interinstitutional negotiations’ outcomes is still missing. The last steps needed are the adoption of the deal by the EU ministers and a vote in the plenary of the European Parliament which should both come this autumn.

According to some EU sources, the matter will not be settled until November as the  Parliament’s current schedule is overburdened due to months of reduced activity during the COVID-crisis.

Despite delays, some of the biggest EU member states have started putting in place microbiological standards already in compliance with the rules the new directive will set.

For instance, advanced national guidelines have already been adopted when it comes to the monitoring of Legionnaires’ diseases, touched upon in Annex III of the new DWD.

During the negotiations at the EU level, the issue of detecting bacterial cultures of Legionella triggered a debate on which approach would be more effective in reducing the risks of Legionnaires’ diseases.

The Legionella bacterium develops primarily in warm, stagnant water. Legionnaires’ disease occurs by inhaling aerosols carrying the Legionella bacteria, with infection leading to pneumonia.

There are more than 60 Legionella species officially described.

However, according to the most important health bodies such as the World Health Organisation (WHO) and the European Centre for Disease Control (ECDC), 96% or more cases of Legionnaires’ diseases are caused by just one specific species, Legionella pneumophila, which causes the deadly form of pneumonia.

In its original proposal backed by the Council, the Commission asked water suppliers not to check for a specific type of the bacteria, but the so-called Legionella species pluralis, basically all Legionella species that reproduce themselves where there is a warmer freshwater system in large public buildings.

The scientific community criticised this approach, opting for checking only for the presence of Legionella pneumophila serogroup 1, which causes most Legionnaires disease infections.

The reason behind scientists’ opposition is that a broader approach would have put at the same level the harmless pathogens and the one causing the deadly form of the disease, creating a useless additional burden for laboratories.

A similar pattern is followed already to prevent E.coli infection, as most varieties of coliform species are not harmful and laboratories focus only on detecting the strain pseudomonas aeruginosa, which is the one that can cause an infection, instead of pseudonoma species.

A compromise was found in the end, as member states were left free to determine their approach to testing, but giving way to adopt more stringent and effective measures, such as testing Legionella pneumophila.

As follows, EU countries will be provided with the option of using alternative Legionella pneumophila testing to achieve the DWD public health protection objectives and are also called upon to establish guidelines for sampling methods of legionella.

The final agreement is aligned with some advanced systems for detection put in place over the recent years that already target Legionella pneumophila.

Mandatory testing in France already requires detection for Legionella pneumophila since 2001 and reported cases in France totalled half the average rate of increases across 30 European countries in 2013-2017.

In Germany, clinical tests usually focus on detecting the virulence of Legionella pneumophila serogroup 1. In drinking water detection is focused on species and pneumophila and when higher concentrations of pneumophila are detected, actions are put in place to lower the presence of the bacteria.

The latest addition to this group of countries, although soon out of the EU, is the UK, whose governmental Standing Committee of Analysts (SCA) has recently introduced the detection of Legionella pneumophila in its authoritative Blue Book, which identifies the methods for the examination of waters and associated materials.

Together with the Netherlands, these three countries have been pioneers in looking for a harmonised approach for testing methods and requirements, launching in 2011 an enhanced cooperation called Four Member States (4MS) Initiative.

[Edited by Zoran Radosavljevic]

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